A large study of medical records found that women in their 70s with stage I, estrogen receptor-positive breast cancer who had radiation therapy after lumpectomy were less likely than those who did not to need a later mastectomy.
The research conflicts with past clinical trials that concluded radiation did not significantly benefit older women with early-stage, hormone-sensitive disease, a group already considered at low risk for local recurrence.
Most women under 70 who have lumpectomy, surgery to remove cancer in the breast along with a small margin of healthy breast tissue, also have radiation therapy afterward to kill any cancer cells that may remain. Women whose cancer recurs locally (within the breast) after lumpectomy often have a mastectomy later.
The Cancer and Leukemia Group B 9343 (CALGB 9343) clinical trial found that for women over 70, radiation therapy after lumpectomy lowered the risk of local recurrence, but with or without radiation the risk of future mastectomy or death from the disease remained nearly the same. These findings suggested radiation therapy was unnecessary for women over 70. The researchers at MD Anderson who conducted this new study explored whether these results were true in clinical practice by analyzing the long-term medical records of women who had lumpectomy.
Medical records for 7,403 women who met the eligibility requirements for CALGB 9343 were obtained from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Participants were 70-79 years old; diagnosed with early-stage, estrogen receptor-positive breast cancer with no cancer in the lymph nodes; and had been treated with lumpectomy. All participants were diagnosed between 1997 and 2002.
Investigators followed 3,771 participants for 10 years, until they had a mastectomy or died, defined as complete follow up; for the remaining 3,632 participants, the median follow-up time was 6.9 years after diagnosis.
This study found that radiation therapy after lumpectomy lowered the risk of local recurrence and future mastectomy in most women over age 70. The exception was women 75 to 79 whose tumors were low to moderate grade and tested negative in the lymph nodes, 28 percent of the study population.
The results also showed:
- The 10-year risk of mastectomy was 3 percent lower for women who had radiation after lumpectomy than for those who did not (6.3 percent without, vs. 3.2 percent with)
- The decrease in risk was not impacted by age, tumor grade, race or other factors
- The 10-year risk of mastectomy for women with high-grade breast cancer saw a 6.7 percent reduction with radiation therapy
How CALGB 9343 Was Different
Researchers on the current study believe that analyzing medical records sheds light on the benefits of treatment in actual practice, rather than in the controlled setting of a clinical trial. In clinical trials, participants are expected to maintain all therapies; outside of a trial, many women do not always remember to take other medicines, such as hormonal therapies. Such factors may raise the risk for local recurrence outside the trial setting, making radiation therapy the more practical way to prevent future mastectomy.
Studies of medical records rely on thorough and clear reporting, so it is important to know this research may not have taken some factors into account. For example, some cancer centers may have offered a second lumpectomy after recurrence rather than mastectomy, or women may have chosen mastectomy over a second lumpectomy themselves. Specific details about the recurrence were not captured in the SEER database, so data were not available to show whether participants had the option of repeat lumpectomy over mastectomy.
Also, no data were available to show whether women took hormonal therapy, which may lower the risk of local recurrence by half. Still, the researchers believe these findings mirror what doctors would know about women’s adherence to taking prescribed pills.
What This Means for You
This study suggests that women over 70 may benefit from radiation therapy after lumpectomy, despite past research that showed otherwise. It also finds that doctors may be able to identify groups who are more or less likely to benefit, which could allow them to offer radiation therapy on a more individualized basis.
If you are considering whether to undergo radiation therapy after lumpectomy, talk to your doctor about these findings to help make the best decision for you.
Albert, Jeffrey M., Pan, I-Wen, et al: Effectiveness of Radiation for Prevention of Mastectomy in Older Breast Cancer Patients Treated With Conservative Surgery. Cancer (October 2012) 118 (19): 4642–4651.