Radiation Therapy Plus Tamoxifen Found Better

Radiation Therapy Plus Tamoxifen Better Than Just Tamoxifen After Lumpectomy

D. McCready et al.

San Antonio Breast Cancer Symposium, December 2004, Abstract # 31

Background and importance of the study: Compared to lumpectomy alone, lumpectomy followed by radiation has been shown to greatly reduce the risk of cancer coming back in the same breast—by about two thirds, or 66%. Hormonal therapy can reduce the risk of recurrence by about 30% to 50%. But doctors have long questioned whether all women need both radiation and hormonal therapy. In particular, they are trying to figure out whether some women with early-stage breast cancer might not need radiation—for example, women with:

• small tumors (less than two centimeters, or about an inch) and
• negative lymph nodes (no cancer cells found in the nodes).

These women have a small chance of the breast cancer coming back. So whole-breast radiation therapy in addition to hormonal therapy might be unnecessary.

The study reviewed here looked at whether radiation therapy further lowers the risk of breast cancer coming back in the same breast. The women in the study were receiving hormonal therapy for node-negative breast cancer that was smaller than two centimeters.

Study design: Canadian researchers randomly assigned 769 women to one of two groups:

• One group received radiation therapy, plus five years of tamoxifen.
• The other group had no radiation therapy and took tamoxifen for five years.

All the women were 50 years or older and had had lumpectomy for node-negative cancer with negative margins. More than 80% of the women had tumors smaller than two centimeters.

The researchers wanted to see if the combination of radiation therapy AND tamoxifen was better than tamoxifen alone in lowering the chances that the breast cancer would come back in the same breast.

Study results: After about five years of follow-up, the researchers found that

• Less than 1% of women who had radiation plus tamoxifen had a recurrence in the same breast.
• In comparison, 8% of the women who took only tamoxifen (no radiation therapy) had their cancer come back in the same breast.

This difference was statistically significant, which means it was not just due to chance.

The researchers also looked at two subgroups of women in the study. One subgroup was women with the smallest cancers—no bigger than one centimeter (less than half an inch). For these 267 women:

• None who had both radiation therapy and tamoxifen had the breast cancer come back in the same breast.
• However, almost 3% who only took tamoxifen had the breast cancer come back in the same breast.

This difference was statistically significant.

The second subgroup was women with hormone-receptor-positive breast cancer. For these 611 women:

• Less than 0.4% (four-tenths of 1 percent) who had radiation therapy and tamoxifen had the breast cancer come back in the same breast.
• However, almost 6% who took tamoxifen alone had a recurrence in the same breast.

This difference was also statistically significant.

Conclusion: Women who had both radiation therapy and tamoxifen were less likely to have breast cancer come back in the same breast than women who only took tamoxifen.

Take-home message: Radiation plus tamoxifen is better than tamoxifen alone at reducing the risk of recurrence after lumpectomy. Even women with very small cancers (less than one centimeter) benefit by getting radiation in addition to tamoxifen. Another similar study found similar results.

These results suggest you shouldn't skip radiation treatment after a lumpectomy, even if you have a very small tumor and are taking tamoxifen or other hormonal therapy.

But remember, no treatment plan is right for everyone. Talk to your doctor about your individual situation and develop a treatment plan that is right for you.