Women over the age of 60 with low-risk breast cancer may not need to receive radiation therapy after surgery

Women over the age of 60 with low-risk breast cancer may not need to receive radiation therapy after surgery, according to a Canadian study reported on Saturday at the 27th Annual San Antonio Breast Cancer Symposium.

Dr. David McCready of Princess Margaret Hospital in Toronto reported on a study in which women over the age of 50 with low-risk breast cancer were randomly assigned to two treatment groups. One group received tamoxifen for 5 years after lumpectomy surgery; the other group received full breast irradiation after surgery followed by tamoxifen for 5 years.

The current treatment standard recommended for most women with early stage breast cancer is breast conservation therapy, consisting of lumpectomy following by radiotherapy. The purpose of the radiotherapy is to kill any tumor cells in the remaining breast area that may have been missed by the surgery. For patients with low-risk disease (small tumors, negative axillary lymph nodes, estrogen receptor-positive), this is typically followed by five years of tamoxifen treatment.

The recommended radiotherapy is an intensive regimen usually requiring daily treatment for up to six weeks. For some women, especially those who are older and may have mobility problems, the logistics of coming to a treatment center every day can be daunting, so much so that some opt to have a mastectomy instead of a lumpectomy in order to avoid the radiation therapy.

Dr. McCready found that the women in the two treatment groups in his study had similar rates of survival, of death from breast cancer, and of metastasis, regardless of whether they had received radiotherapy. However, the rate at which disease recurred in the breast was significantly different between the two groups, with a recurrence rate of 7.7% in the group that did not receive radiotherapy compared with 0.6% in the group that did.

Dr. McCready examined the data to see if age and tumor size affected the rate of recurrence in the breast. He found that women over 60 tended to have low recurrence rates whether or not they received radiation therapy, and that the rate at which cancer recurred in the breast was affected by how large the original tumor had been. In women over 60 whose tumors were more than 2 centimeters in diameter, the recurrence rate was about 11%, and in women whose tumors were 1-2 centimeters in diameter, the recurrence rate was 6%-7%.

For women with very small tumors (less than 1 cm, approximately one-half inch in diameter), however, the recurrence rate was very low-1.2% at 5 years and 3% at 8 years. These rates are higher than those seen in women who received radiation therapy (where no breast recurrences were seen), but in absolute terms, they are quite low. Based on these findings, Dr. McCready suggested that women over the age of 60 with low-risk breast tumors may consider treatment with tamoxifen only, avoiding the physical and emotional difficulties of radiotherapy.