Ask-the-Expert Online Conference
Questions from this conference
- MRI instead of yearly mammograms?
- Genetic testing for all women with breast cancer?
- Follow-up screening for recurrence?
- Tamoxifen side effects. Suggestions?
- MRIs for sisters of diagnosed?
- Taking Arimidex past 5-year mark?
- Does elective surgery increase risk of recurrence?
- Does estrogen ring increase risk of recurrence?
- Mammogram safe after radiation?
- Yearly MRIs for large-breasted women?
- Arimidex beneficial despite side effects?
- Femara after tamoxifen to prevent recurrence?
- Prophylactic oophorectomy or hysterectomy?
- Prophylactic mastectomy to reduce risk?
- Tamoxifen after prophylactic surgeries?
- Do birth control pills increase risk?
- Calcifications in remaining breast increase risk?
- Low-fat diet to reduce risk of recurrence?
- Does alcohol increase risk of recurrence?
- Prophylactic mastectomy after DCIS?
- Insurance coverage for prophylactic surgeries?
- Prophylactic oophorectomy after treatment?
- Prophylactic surgery for family history?
- Risk reduction, early screening for daughters?
- Keep genetic testing confidential?
- New screening test for dense breasts?
- Thermography for early detection?
- Recommended screening for family history?
- Late pregnancy and increased risk?
- Should I see doctor for armpit pain?
- Risk of recurrence after pregnancy?
- New breast cancer genes identified?
- Why is tamoxifen recommended for LCIS?
The materials presented in these conferences do not necessarily reflect the views of Breastcancer.org. A qualified healthcare professional should be consulted before using any therapeutic product or regimen discussed. All readers should verify all information and data before employing any therapies described here.
This conference was made possible by an unrestricted educational grant from the Leonard and Helen R. Stulman Charitable Foundation.
This has been a presentation of Breastcancer.org, produced by LiveWorld, Inc. Copyright 2006. All rights reserved.
- Question from CArlene: Do you recommend an MRI instead of yearly mammograms?
- Answers - Lynn Hartmann It really depends on the level of density in the breast tissue and also the risk status of the patient whether an MRI (magnetic resonance imaging) might be appropriate. Generally, we're using breast MRIs for very high-risk women, such as BRCA carriers and women with dense breast tissue.
- Beth Baughman DuPree, M.D., F.A.C.S. In my practice, MRI is used predominately in assessment for multi-focal breast cancers, for women whose cancers were not detected mammographically, and also those patients, as Dr. Hartmann has discussed, who are at high risk for developing breast cancer. There are new tests on the horizon such as Positron Emission Mammography (PEM) that are currently being used on a trial basis. They have tremendous potential in the future for the screening of high-risk women. The PEM is a form of a PET scan specifically for the breast.
- Question from CArlene: Do you suggest genetic testing for all women with breast cancer?
- Answers - Lynn Hartmann No, we don't. It depends on the family history and the age of the woman when she is diagnosed, and also whether or not the information from genetic testing would help direct her care or the care of someone in her family.
- Question from Teddy-2: I had diagnosis of stage I, followed by lumpectomy and radiation and am now on Femara. What is the recommendation for follow-up screening for recurrence?
Generally, a physician or nurse practitioner exam every six months for five years, including annual mammography for both her affected breast and her other breast. There are different schools of thought about how aggressively to pursue tests or markers in this setting. Most studies do not show a benefit with aggressive testing.
If there is a problem, generally the patient has symptoms that direct us to the source of the problem. Multiple tests in this setting, like bone scans or CT (computerized axial tomography) scans, can turn up false positive results that lead to anxiety and no benefit.
- Question from Connie: I was diagnosed with ductal carcinoma in situ (DCIS), up-dated to pre-cancer small lesion. I had surgery and seven weeks of radiation. I was put on tamoxifen and could not handle side effects, so was told I could try Arimidex or just do all necessary follow-ups. I am 76 and not eager for any more side effects. I was on HRT for 26 years and am dealing with effects of stopping. Could you comment, please?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. With a non-invasive breast cancer at the age of 76 with appropriate surgical treatment and radiation therapy, it is within the realm of appropriate treatment to stop the tamoxifen therapy. Try the Arimidex (chemical name: anastrozole) or follow through with close clinical follow-ups, meaning breast exams every six months and follow up mammography.
- Question from Stella: My now 37-year-old daughter was diagnosed with invasive breast cancer in 2002, now a Stage IV. I have three other daughters, two younger and one older than the one with breast cancer. Thankfully, all my other daughters have had clear mammograms. Should they also have MRIs, even though insurance won't cover them?
- Answers - Lynn Hartmann If that is the only breast cancer in the family, that in and of itself does not say it's a hereditary process, so I would not recommend MRIs for the sisters. I think certainly the older sister should be examined and have a mammogram and someone should take a good family history, see if there are other breast or ovarian cancers in the family. Or is it an Ashkenazi Jewish family, which would raise the index of suspicion that it might be hereditary? Bottom line: try to determine if this is hereditary or not, but I would not automatically recommend breast MRIs for the family.
- Beth Baughman DuPree, M.D., F.A.C.S. I agree completely about the additional family history and would certainly suggest that the sisters be vigilant about their breast exams and be followed by their gynecologists as well on a regular basis.
- Question from Amma: Does anyone have any input on taking Arimidex longer than the five-year mark? I took tamoxifen for two years and Arimidex for three, and my doctor says continuing might be beneficial.
- Answers - Lynn Hartmann That's a good question, and we're looking for answers to that with ongoing clinical trials. The clinical trial that looked at Femara (chemical name: letrozole), an aromatase inhibitor similar to Arimidex (chemical name: anastrozole) or Aromasin (chemical name: exemestane), examined five years of Femara after five years of tamoxifen. Now it is looking at five additional years of Femara (a total of 10 years) compared to placebo. Your question is a good one, but I don't know a specific answer at this time. And most physicians are stopping after two to three years of tamoxifen plus two to three years of an aromatase inhibitor.
- Question from Jan: Does having elective surgery after completing treatments increase the risk of recurrences?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. I know of no data that would suggest that an elective procedure increases the risk of recurrent breast carcinoma.
- Question from Marsha-3: I am 61, and my gynecologist recently prescribed an estrogen ring to help with vaginal dryness and atrophy. She says it is perfectly safe. Do you agree, or should I be worried about estrogen entering my bloodstream?
- Answers - Lynn Hartmann I would say that I think that is a safe measure for you. There some absorption of estrogen into the bloodstream, but it is a low amount.
- Beth Baughman DuPree, M.D., F.A.C.S. I agree with Dr. Hartmann. This is one of those situations in life where the risks and benefits of a medication need to be looked at. Clearly your gynecologist feels that the vaginal dryness and atrophy are significant enough symptoms in your life to warrant treatment. And although the amount of estrogen absorption is minimal, it does have effect, as it will help to change the environment of the vaginal area.
- Question from Nikki: I am concerned about having another mammogram after having had radiation treatment. Isn't this just radiating a breast that has already been heavily radiated? Would sonogram alone be enough for follow-up?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. Ultrasound or sonography is not a modality that is used for breast cancer screening. It is used as a diagnostic tool when an abnormality is found on either mammogram or clinical exam. The dosage of radiation exposure from a digital mammography is so small that the benefit of early detection of future cancers far outweighs any potential risk of additional radiation therapy. The dosage of radiation is not one that is used for treatment such as radiation therapy.
- Question from Rusina: I have heard that MRIs are more effective than mammograms for large-breasted women in detecting initial cancer occurrence or recurrence. Should I ask for an MRI instead of a mammogram for my yearly check-up? I had surgery three times on the affected breast and find that mammograms have become very painful, with effects lasting up to a month.
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. MRI is not an appropriate screening tool in the general population and digital mammography machines are now available that can accommodate large-breasted women. The mammogram is still at this point in time our tool that we use for screening in general and should be the starting point for the annual exam. If a question is raised on the mammography, at times it may be appropriate to follow up with an ultrasound and/or MRI scan prior to another biopsy, given the history of surgery three times previously in one breast.
- Question from Snyder: My wife had a cancerous tumor removed from her breast and has gone through 44 days of radiation. The doctor will put her on Arimidex next week. I read the reactions people get from it and do not like it. My wife will not even take aspirin unless she really has to. Do you think this is really necessary?
- Answers - Lynn Hartmann Actually, Arimidex is quite well tolerated by most women. The most common side effects experienced are hot flashes and sometimes, joint achiness. However, an important side effect is that it can lower bone density, and thus for most women we check a baseline bone density before starting the Arimidex. For women with low bone density, tamoxifen may be a better choice.
- Question from Joan: Is Femara after tamoxifen really the new miracle to help prevent the cancer from coming back after five years of tamoxifen?
- Answers - Lynn Hartmann Femara does help to further reduce the risk of recurrence of breast cancer after tamoxifen. For every woman's situation, we must determine how great her risk of recurrence is after tamoxifen and whether or not there is significant justification for the Femara. In one example, if a woman had only a 10% risk of recurrence after tamoxifen, the Femara might provide only two or three percentage points lower risk, in which case the side effects she experienced could outweigh the benefit. So it is judged on a case-by-case basis, and it depends on the women's risk of recurrence whether we recommend Femara after five years of tamoxifen.
- Question from Sarah: I was diagnosed a year and a half ago with hormone-positive breast cancer and went through dose-dense treatment, etc. Now I have found out that I am positive for the BRCA2 mutation. I am making plans to have a prophylactic oophorectomy and hope to have it done laparoscopically [through a belly-button incision]. Is it enough to just get the ovaries and fallopian tubes removed or should I consider a full hysterectomy?
- Answers - Lynn Hartmann Generally, we recommend the removal of ovaries and tubes and a thorough evaluation by the surgeon. A hysterectomy is not routinely recommended although for some women this is preferred. Again, this needs to be considered on a case-by-case basis, but it is not necessarily done routinely.
- Question from LMG: I am 39, BRCA1 positive, and currently undergoing MRI surveillance every six months. My 47-year-old sister died of breast cancer last month. Am I being foolish not to have prophylactic removal of my breasts? I had my ovaries out at 36 to reduce risk already. Should I start tamoxifen?
Beth Baughman DuPree, M.D., F.A.C.S.
The decision to do prophylactic surgery is often a very difficult decision to make. Prophylactic mastectomy does not remove all risk of developing breast cancer but can significantly reduce the risk of developing an invasive cancer in the future.
A very thorough discussion should take place between you the patient, your surgeon and potentially your oncologist to help you come to a decision about what is absolutely best for you. There is no right or wrong answer, and depending upon what your goals are through this process you should be able to come up with a plan of action for your future surveillance and/or risk reduction.
Tamoxifen can certainly help to decrease the risk of developing an estrogen-receptor-positive tumor, but there are no foolproof methods to keep you from developing a breast cancer. Therefore, as I said before, work with your physician to determine what is best for you.
- Lynn Hartmann Issues that can help with this decision include the ease of your breast exam and the density of your breast tissue. Having had your ovaries removed should provide some risk reduction. I would reiterate what Dr. DuPree has said, that this is very much an individual decision.
- Question from DonnaM: I know there is some data to suggest the use of tamoxifen in high-risk women without a breast cancer diagnosis, but is there any reason why a woman with BRCA1 or 2 would need tamoxifen AFTER having prophylactic surgeries if she has not been diagnosed with the disease?
- Answers - Lynn Hartmann That's a very good question. I would say if you had prophylactic mastectomy there would be no need to take tamoxifen.
- Beth Baughman DuPree, M.D., F.A.C.S. I completely agree.
- Question from Charlene: Dr. Hartmann, I have recently been diagnosed with estrogen-receptor-positive cancer. My daughter has been on birth control pills for the past five years. Should we consider having her stop taking them?
- Answers - Lynn Hartmann There are good studies available now that do not show an increase in risk of breast cancer in women who take birth control pills. I think that it is safe for your daughter to continue to use the pill.
- Question from Peggy: I am 50 years old and was diagnosed and treated for breast cancer two years ago. I had a mastectomy with immediate reconstruction. I had negative sentinel lymph nodes and four rounds of Taxol. I took tamoxifen for one year and switched to Femara for the last year. On my recent mammogram, new benign calcifications were identified. What is my risk for tumor in my remaining breast? What are the implications of calcifications?
- Answers - Lynn Hartmann In general, with no family history the risk of a cancer in the opposite breast is about 1% per year out to about a 15% risk overall. To my mind, the benign-appearing calcifications do not suggest an increase in that risk.
- Beth Baughman DuPree, M.D., F.A.C.S. The fact that the calcifications are new would raise a question in my mind to make sure that they have been evaluated appropriately with spot magnification views and assessment by either a second radiologist or breast surgeon to determine their nature. If there is any question that they are anything but benign, a biopsy may be indicated.
- Question from Nance: I recently heard that low-fat diets do not prevent breast cancer. What is the evidence that they can prevent an occurrence in someone who had early-stage cancer? Do they work for hormone-positive as well as hormone-negative cancer? Thank you.
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. We do not have tremendous evidence to support a low-fat diet decreasing the risk of breast cancer. What we do know is that women who decrease their body fat and exercise regularly, more than three hours per week, can decrease their risk of breast cancer by approximately 20%. This may be due to an overall decrease in circulating estradiol [a type of estrogen] that may in turn decrease the stimulation to cells that are potentially pre-cancerous. If a low-fat diet can help decrease a woman's overall body fat, it may indirectly help to decrease her risk.
- Question from Smiley: Does anyone know for sure the exact risks of alcohol consumption and the recurrence of breast cancer? I am taking Arimidex, but I am also concerned about relaxing with a glass or two of wine at night. Has there been a study done on this particular issue?
I don't know of studies that have looked at this particular question, important as it is. In general, I think a glass of wine a few times a week is reasonable. Sometimes it helps people stimulate their appetite or reduce their stress, which are generally positive. I've not seen data to suggest that such a practice would increase the risk of recurrence of a breast cancer.
Editor's Note: A 2009 study reported at the San Antonio Breast Cancer Symposium found that women who drank three or more alcoholic drinks per week were 34% more likely to have a recurrence and 51% more likely to die from breast cancer compared to women who didn't drink.
- Question from AWatts: I just had a mastectomy on the left side due to DCIS. I do not want to take tamoxifen. I am considering a mastectomy on the other side because next time around I may not be so lucky. Is this too aggressive?
Beth Baughman DuPree, M.D., F.A.C.S.
Your decision to have a prophylactic mastectomy needs to be based on several factors: a very careful assessment of your family history and true risk, as well as the ability to screen the opposite breast with mammography and clinical exams. It is not unreasonable, particularly for younger women, to feel that their overall lifetime risk of developing an invasive breast cancer and the stress that goes with that might lead them to undertake a mastectomy as an option.
But this decision needs to be weighed very carefully and should be thought out very clearly prior to moving forward with that particular surgery. In my population of patients, those with DCIS tend to choose prophylactic surgery for the opposite breast more often than women with invasive cancers. This is because prophylactic surgery can certainly decrease the risks of an invasive cancer in the opposite breast for women with DCIS. And that removes the need in the future for chemotherapy or radiation therapy. But as we have said before, this is certainly a decision that needs to be discussed very thoroughly with your physician, medical oncologist, and plastic surgeon.
- Lynn Hartmann In studies of DCIS that have tracked the likelihood of a cancer in the opposite breast, the number is often lower than someone might expect. In one large trial after about six to seven years of follow-up, approximately 4% of women developed a second breast cancer in the opposite breast. It's important for women to understand the actual risk they have as they make those decisions.
- Question from Ang: I am concerned about the cost of elective surgery. Will my insurance cover the cost of removal of breasts and/or ovaries?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. If the woman's risk is such that prophylactic surgery has been suggested by either her surgeon or medical oncologist, I have found that most insurance companies will provide coverage for that surgery as it is not considered elective but prophylactic. I personally would not perform a prophylactic surgery on a patient who did not have significant risk of breast or ovarian cancer.
- Lynn Hartmann I agree with Dr. DuPree. Occasionally the insurance companies will balk at reimbursement, but if the physician provides documentation of the need for the surgery, they usually do provide coverage.
- Question from KC: My ob-gyn doctor has suggested that I have a prophylactic oophorectomy. I completed treatment—lumpectomy, chemo and radiation—two years ago for Stage III breast cancer (six positive nodes). The chemo put me into instant menopause at age 47, and I've been on Aromasin for nearly two years. I have no family history of breast cancer or ovarian cancer. I am concerned about possible ill effects on my heart, bones, and loss of male hormone production. What is your opinion?
In general we consider prophylactic oophorectomy in women whose risk of ovarian cancer is significant, such as those who are BRCA carriers or those who have a strong family history of breast cancer, with or without ovarian cancer. In your particular situation, this does not seem to be the case.
Or in other younger women who've had breast cancer, we may remove the ovaries to cut down the ovaries' production of estrogen. Since you have already gone through menopause with your chemotherapy, your ovaries are not making much estrogen. I think that you should discuss the rationale for having your ovaries removed with your oncologist in addition to your gynecologist.
- Question from KF: I am considered to be in a high-risk category as I have two first-degree relatives who had breast cancer. One is a survivor and the other passed away from metastatic breast cancer. There is also a family pattern for breast/ovarian cancer. We have been genetically tested and do not have the BRCA1 or BRCA2 mutations. Should I consider prophylactic mastectomy? What are some other ways to reduce my risk?
Your question is very important because many women with a family history such as yours who are tested do not have an abnormality in BRCA 1 or 2. Our current technology cannot find all the mutations in these genes. Or perhaps there are other susceptibility genes that we cannot yet test for. A decision to proceed with prophylactic surgery is complex and very much an individual preference type of decision. It depends in part on ease of your breast exam and the density of your breast tissue on mammography. Breast MRI may also be an option.
The goal of surveillance is to pick up any cancer that might develop as early as possible. There is no one recommendation for prophylactic surgery in women such as yourself. You may be a candidate for a chemotherapy prevention study that is currently ongoing. Or tamoxifen is also a risk-reduction strategy, depending on your preference and other health issues.
- Question from Shelagh: I have had breast cancer and there is history of prostate and breast cancer on my husband's side of the family. As a mother of two adult daughters I have been unable to get any concrete advice on how my girls can reduce their risk of breast cancer other than starting mammograms earlier. What else should they do? Thank you for your response.
- Answers - Lynn Hartmann Depending on your age at diagnosis and the ages of your husband's relatives with breast cancer, it might be wise to have a visit with a genetic counselor about the possibility of a hereditary process in your family or in your husband's family and whether or not testing would be beneficial. In general, early mammography would be recommended for your daughters as a starting point.
- Beth Baughman DuPree, M.D., F.A.C.S. In addition, I think it's very important for young women who are in a high-risk category to adopt a healthy lifestyle that includes exercise and strength training, for several reasons. One is the benefit of decreased risk from the exercise as well as the overall bone density enhancement with strength training, as most women in high-risk families do not choose to take estrogen replacement after menopause. Therefore starting strength training early can help prevent bone loss.
- Question from Eadie: Because of my family history (breast and prostate cancer on both sides), I would like to have genetic testing. But I am very concerned about the information being given to my employer or otherwise getting out. Do I need to be worried about keeping this confidential?
- Answers - Lynn Hartmann You raise a very valid point, but there have been very few instances of discrimination in employment or insurance because of genetic testing information.
- Question from Mimi55: I heard that there is a new scan available for women with dense breasts. It uses a radioactive tracer, I believe. Can you give us more information on this, and is reasonable to ask for this instead of my yearly MRI?
Beth Baughman DuPree, M.D., F.A.C.S.
The scan that you're asking about is the PEM scan, the PET scan for the breast as I had previously mentioned. The tracer is a radioactive tracer that is injected, and then the breast is scanned to try to detect very early cancers and also evaluate for multiple areas of cancer in the same breast.
At this point in time the PEM is available at certain radiology facilities, but it has not yet replaced the MRI. There are going to be studies in the very near future that will help us to determine whether PEM has the ability to replace other studies, or if it will be used in addition to mammography, ultrasound, and MRI to help to give us a clearer picture of exactly what is happening within the breast tissue. Biopsy of an abnormal area is still the gold standard by which we practice medicine. Therefore, abnormal areas on studies such as MRIs and PEMs would need to have a confirmatory biopsy to prove that they are truly cancer.
- Question from Nigar: What are your thoughts on thermography as an early detection tool?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. I do not recommend thermography as a screening tool. [This is a scan that measures heat produced by the breast tissue.] It has not been shown to be as effective as digital mammography for detection of breast cancer.
- Question from Kayaykaysc: What testing should I pursue if I have no symptoms, but a strong family history?
- Answers - Lynn Hartmann In general we recommend seeing your physician or nurse practitioner every six months for a thorough examination, your own monthly breast self-exam, and an annual mammogram. Depending on the density of your breast tissue and the extent of your breast cancer risk, additional surveillance, such as a breast MRI, may be needed.
- Question from Gina: My mother passed away of breast cancer at age 42. I'm 40 now with no children. I'm recently married and considering having a child. I've heard that children late in life (or no children at all) increases breast cancer risk. Any thoughts on that? Thank you!
- Answers - Lynn Hartmann There is a slight increased risk of breast cancer in women who have never had children or had their first child late in life (after age 30). The emphasis, however, is on the word "slight." It's certainly important for you to understand your risk of breast cancer. If there are other relatives in the family besides your mother who have breast cancer, or if you're from an Ashkenazi Jewish family, you may wish to visit with a genetic counselor to understand your risks as you make this decision.
- Beth Baughman DuPree, M.D., F.A.C.S. You can read more about risk reduction in the special section, Lower Your Risk, here at www.breastcancer.org.
- Question from Jayne: I get confused about breast self-exams. I have been having pain in my left armpit—I can't feel anything on the outside, but I feel that there is something that I cannot palpate. Is this something I should see my gynecologist or my primary care doctor about?
- Answers - Beth Baughman DuPree, M.D., F.A.C.S. It's understandable to be confused about breast self-exam, but what's most important is that you're doing it. Because of the fact that you have found something that doesn't feel exactly correct to you, I would suggest seeing your gynecologist for a good clinical breast exam. You may be feeling tenderness within your breast or armpit area that has a perfectly rational explanation, but using your own sense that something isn't exactly right to guide you to your gynecologist is certainly appropriate.
- Question from Jhop: What is the risk of recurrence related to pregnancy post-treatment (stage I)? I'm 36 and recognize that there are pregnancy risks based on my age alone, but I can't seem to get a clear sense of whether there is a greater risk of recurrence.
- Answers - Lynn Hartmann You're asking a very good question. The studies that have been done of risk of recurrence of breast cancer after pregnancy have been retrospective [surveying the women after the recurrence happened]. They have not shown an increase in risk in women who've had breast cancer and then get pregnant versus women who do not have a subsequent pregnancy. This is certainly a good question to bring up with your oncologist, however.
- Beth Baughman DuPree, M.D., F.A.C.S. In my patients who have had breast cancer who choose to pursue pregnancy after their treatment of breast cancer, the recommendations of timing for the pregnancy can certainly vary based upon the stage of the tumor, the treatment, the estrogen or progesterone receptor status and the age of the patient. All of these factors need to be carefully weighed in order for the woman to be able to make a decision about whether or not to get pregnant and the timing of that pregnancy.
- Question from Lisa: Are there any new breast cancer genes on the horizon in addition to BRCA1 and 2?
- Answers - Lynn Hartmann There has been a lot of intense research to try to identify additional breast cancer susceptibility genes besides BRCA1 and 2, but to date we have not found any as important as these two. We are still learning that other genes may affect the function of BRCA1 and 2, and testing may become more refined within the next few years. Certain alterations in BRCA1 and 2 whose function is not currently understood may also be better defined in the next few years. Bottom line: many women today get a result [from testing] that is uninformative. There may be a slight change in the gene and we do not know if that's a significant mutation or not. So there are studies going on to determine whether those fairly common types of changes are really meaningful in predisposing women to cancer.
- Question from Nunz: Why is tamoxifen recommended for women with LCIS if we aren't sure it's estrogen-receptor-positive?
- Answers - Lynn Hartmann In the large U.S. prevention trial on non-invasive disease women with lobular carcinoma in situ (LCIS) were eligible. There was a significant reduction of their risk of subsequent breast cancer with tamoxifen. So we consider tamoxifen a valid option for women with LCIS.
- Beth Baughman DuPree, M.D., F.A.C.S. LCIS is not cancer; it is a marker for an elevated risk of developing breast cancer. Therefore, the rationale for using tamoxifen is for those cancers that are estrogen-receptor-positive, we are attempting to block those cells from dividing and turning into cancer. Tamoxifen would not be effective in tumors that are estrogen-receptor-negative, but a majority of breast cancers are estrogen-receptor-positive. Therefore, we derive the benefit of tamoxifen from that fact.