Hormonal therapy side effects may include hot flashes, night sweats, and joint pain. The study reviewed here found that when women taking hormonal therapy had these side effects, breast cancer was less likely to come back compared to women on hormonal therapy who didn't have these symptoms.
Tamoxifen and aromatase inhibitors (two types of hormonal therapy medicines) are usually taken for 5 years after surgery (and possibly radiation and chemotherapy) to lower the risk of hormone-receptor-positive early-stage breast cancer coming back in post-menopausal women. Because the hormonal therapy medicines are taken after surgery, they're called adjuvant hormonal therapy.
Tamoxifen works by blocking the effects of estrogen on breast cancer cells. Aromatase inhibitors work by lowering the amount of estrogen in the body. The aromatase inhibitors are:
Hot flashes and night sweats -- also known as vasomotor symptoms -- can happen while you're taking either tamoxifen or an aromatase inhibitor. Hot flashes and night sweats happen because of the effects these medicines have on estrogen. These side effects are more likely to happen if you're taking tamoxifen. Joint pain is more common with aromatase inhibitors than with tamoxifen. Doctors aren't exactly sure why aromatase inhibitors can cause joint pain.
In this study, researchers looked at the medical histories of almost 4,000 post-menopausal women who were part of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study. The women all had been treated for hormone-receptor-positive early-stage breast cancer and then took either tamoxifen or an aromatase inhibitor to lower the risk of the breast cancer coming back. After the women had taken either tamoxifen or an aromatase inhibitor for 3 months, the researchers looked to see whether each woman had new hot flashes, night sweats, or joint pains during the 3 months. The researchers followed the women for about 9 years to see if any of the women had breast cancer come back.
Women who had new hot flashes, night sweats, or joint pain after 3 months of hormonal therapy were less likely to have breast cancer come back than women who didn't have hot flashes, night sweats or joint pain. This was true whether the women took tamoxifen or an aromatase inhibitor.
Women who had new joint pain but not new hot flashes or night sweats were less likely to have breast cancer come back than women who had new hot flashes or night sweats but no new joint pain. Women who had new hot flashes and night sweats AND new joint pain were less likely to have breast cancer come back than women who had EITHER new hot flashes or night sweats alone or new joint pain alone.
The researchers aren't sure why having these side effects while taking hormonal therapy is linked to a lower risk of the cancer coming back. Because these side effects can be troubling, doctors should know about this research and explain the link between side effects and a lower risk of cancer coming back to women taking hormonal therapy. Knowing that side effects might indicate a reduced risk of the cancer coming back might help some women stick with treatment despite the side effects.
If you're taking hormonal therapy medicine to reduce the risk of breast cancer coming back, you might have some of the side effects mentioned in this study. If the side effects are a problem, talk to your doctor about managing them or switching medications. Don't let side effects stop you from doing all you can to keep your risk of the cancer coming back as low as it can be.
For more information on why it's so important to stick to your treatment plan, visit the Breastcancer.org Staying on Track with Treatment section.
LONDON, Oct. 29 (MedPage Today) -- The hot flashes, night sweats, and joint symptoms that come with adjuvant endocrine treatment for breast cancer may signal a reduced likelihood of recurrence, researchers found.
For women who developed new vasomotor and joint symptoms within the first three months of treatment with estrogen-depletion or blockade drugs, the nine-year recurrence rate was reduced by 11.4% compared with the rate in women who did not have those symptoms, Jack Cuzick, Ph.D., of the University of London, and colleagues reported online in the Lancet Oncology.
Their retrospective analysis assessed the relationship between the reported incidence of vasomotor or joint symptoms and breast cancer recurrence in the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial.
Of 3,964 women with hormone-receptor-positive tumors (mean age at entry, 63.9), 1,486 (37.5%) reported new vasomotor symptoms at three months.
These women had lower subsequent recurrence rates than those who did not report these symptoms: 223 women during 10,752 women-years of follow-up versus 366 during 11, 573 woman-years of follow-up, respectively (hazard ratio 0.84, 95% CI 0.71 to 1.00, P=0.04).
This was after adjustment for age, body mass index, previous hormone-replacement therapy, nodal status, and tumor size and grade.
The decrease in recurrence rates was similar among women treated with either anastrozole or tamoxifen.
A greater decrease in breast cancer recurrence was also seen for the 1,245 of 3,964 (31.4%) eligible women who reported new joint symptoms at three months compared with those not reporting those symptoms (158 during 9,242 women-years of follow-up versus 366 during 11,573 women-years of follow-up; adjusted HR 0.60 (95% CI 0.50 to 0.72, P<0.0001).
Compared with women who reported none of these symptoms at three months, women who reported both side effects had an absolute decrease in recurrence of 11.4% (95% CI 9.9 to 12.5) after nine years.
Those with joint symptoms only had a 10% (95% CI 8.7 to 10.8) absolute decease and those with vasomotor symptoms only had a 6% (95% CI 6.2 to 7.2) absolute risk decrease.
This analysis supports an inverse association between the occurrence of vasomotor symptoms and breast cancer recurrence previously reported for tamoxifen, and now extended to the aromatase inhibitor anastrozole and to the presence of joint symptoms, the researchers wrote.
All of these symptoms are believed to be related to lowered estrogen concentrations, although the specific underlying cause of aromatase-inhibitor-induced joint symptoms is still unknown, they said.
In discussing study problems, the researchers noted that because this study included only women who began their allocated treatment at baseline, and endocrine symptoms were measured at the three-month follow-up, their reported adherence to treatment during this period was high (99.7%) and was unlikely to have affected symptom reports.
Although it could be argued that symptoms could lead to lower subsequent adherence, the opposite was actually true, the researchers said.
Additionally, they said, the appearance of symptoms could lead to the use of medicines that could also decrease recurrence as an additional effect. Details of aspirin use and that of other non-steroidal anti-inflammatory drugs were not collected accurately, they noted.
These findings have important implications for communication with patients with symptoms caused by endocrine therapy, the investigators wrote.
Awareness of the relationship between early treatment symptoms and a beneficial response to therapy might be useful when reassuring patients who present with them, and might help to improve long-term treatment adherence.
The findings also raise questions about the effect that drugs aimed at easing endocrine symptoms might have on the efficacy of endocrine treatment if they target the same mechanism of action, the researchers concluded.
The study was funded by Cancer Research UK and AstraZeneca, maker of Arimidex.
Dr. Cuzick has received research funds from AstraZeneca and has acted as a consultant to AstraZeneca and Novartis.
Primary source: The Lancet Oncology Source reference: Cuzick J, et al "Treatment-emergent endocrine symptoms and the risk of breast cancer recurrence: a retrospective analysis of the ATAC trial" Lancet Oncology 2008: DOI: 10.1016/S1470-2045(08)70259-6.
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