Tamoxifen Gel Reduces DCIS Recurrence Risk as Well as Tamoxifen Pills

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DCIS (ductal carcinoma in situ) is the most common form of non-invasive breast cancer and is considered stage 0 cancer. While DCIS isn’t life-threatening, it increases the risk of developing invasive breast cancer later in life.

DCIS usually is treated with surgery to remove the cancer – lumpectomy in many cases. After surgery, many women have radiation therapy to reduce the risk of the DCIS coming back (recurrence). If the DCIS is hormone-receptor-positive (most are), hormonal therapy also is usually recommended after surgery.

Of the adjuvant hormonal therapy choices, tamoxifen has been approved the longest and is approved to treat both premenopausal and postmenopausal women. The other main type of hormonal therapy medicine is the aromatase inhibitors, which are approved to treat only postmenopausal women. Studies are looking at whether the aromatase inhibitors are effective in reducing the risk of recurrence in people with DCIS.

Right now, tamoxifen comes in two forms:

  • a pill that is taken once a day
  • a liquid (brand name: Soltamox) that is taken once per day

In most cases, tamoxifen is taken for 5 years after DCIS surgery.

Since its approval by the U.S. Food and Drug Administration in 1998, tamoxifen has been used to treat millions of women and men diagnosed with hormone-receptor-positive breast cancer and DCIS. Still, tamoxifen does have side effects, some of them serious, including:

  • higher risk of blood clots
  • higher risk of stroke
  • higher risk of uterine cancer
  • hot flashes/night sweats
  • fatigue
  • mood swings
  • depression
  • loss of libido

These side effects are why many women stop taking tamoxifen early, before the 5 years is up.

A small, early study has found that an experimental gel form of tamoxifen that is applied directly to the breast area of women diagnosed with DCIS stopped cancer cell growth as well as tamoxifen pills and caused fewer side effects.

The research was published in the July 15, 2014 issue of Clinical Cancer Research. Read the abstract of “A Randomized Phase II Presurgical Trial of Tansdermal 4-Hydroxytamoxifen Gel versus Oral Tamoxifen in Women with Ductal Carcinoma In Situ of the Breast.”

This study was a phase II clinical trial, which means it was looking at how effective the new tamoxifen gel is. Phase II trials are small – usually between 25 and 100 people. The people in the study are given the new treatment, in this case the tamoxifen gel, and the researchers watch to see if the treatment has some benefit.

In this study, the researchers randomly assigned 26 pre- and postmenopausal women newly diagnosed with hormone-receptor-positive DCIS to be treated with either:

  • a tamoxifen pill and a placebo gel (13 women)
  • a placebo pill and tamoxifen gel (13 women)

The women were treated with tamoxifen for 6 to 10 weeks before they had DCIS surgery. All the women took a pill once a day and applied a gel to their breast area once a day, so no one knew who was getting which form of tamoxifen.

After the DCIS was removed, the researchers used a special stain to see how many DCIS cells were positive for Ki-67. Ki-67 is a protein in cells that increases as they prepare to divide into new cells. The more positive cells there are, the more quickly they’re dividing and forming new cells.

The researchers wanted to know if the tamoxifen gel would stop cell growth as well as the pill form of tamoxifen. So they looked to see if there were differences in the Ki-67 levels in DCIS that had been treated with tamoxifen gel and DCIS that had been treated with tamoxifen pills.

The results showed that both the tamoxifen gel and the tamoxifen pills lowered levels of Ki-67 by the same amount, suggesting that both forms of tamoxifen are equally effective at stopping cancer growth.

The researchers also found that no matter which form of tamoxifen the women were treated with, they all had about the same level of tamoxifen in their breast tissue.

But the women who were treated with the tamoxifen gel had blood levels of tamoxifen that were more than 5 times lower than women who were treated with tamoxifen pills. This is important because lower levels of tamoxifen in the blood also lowered the levels of proteins that cause blood clots, which can lead to stroke. Lower tamoxifen blood levels also reduce the risk of uterine cancer.

“The gel minimized exposure to the rest of the body and concentrated the drug in the breast, where it is needed,” the researchers said. “There was very little drug in the bloodstream, which should avoid potential blood clots as well as an elevated risk for uterine cancer.”

The researchers also think that the tamoxifen gel could be used by women at high risk for breast cancer but who haven’t been diagnosed to reduce that high risk, much in the same way tamoxifen pills are used preventively.

It’s important to know that this is an early study and it may be several years before tamoxifen gel is on the market. A large phase III trial must be done to compare the safety and effectiveness of the tamoxifen gel to tamoxifen pills.

Still, if you’ve been diagnosed with DCIS or are a woman at high risk for breast cancer who hasn’t been diagnosed, you may want to talk to your doctor about this study. If you’re willing to participate in a clinical trial, you may be able to be part of the phase III trial on tamoxifen gel when and if it happens. Visit the Breastcancer.org Clinical Trials pages for more information.

And stayed tuned to Breastcancer.org for updates on research on tamoxifen gel.

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