August 28, 2012
2 min read

Radiation after lumpectomy reduced risk for future mastectomy

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Older women with early breast cancer who received radiation therapy after conservative surgery were less likely to require a mastectomy later in life than women who did not receive radiation therapy, according to study results.

After conservative surgery for invasive breast cancer, radiation therapy to the breast has been shown to improve survival and increase the possibility of long-term breast preservation by preventing a local recurrence that would require salvage mastectomy. However, because the risk for local recurrence is particularly low for older women, several studies have investigated the practicality of omitting radiation therapy in this demographic.

In this study, the researchers used data from the SEER-Medicare observational cohort to determine the effect of radiation therapy on the risk for mastectomy among older women with stage I, ER-positive breast cancer.

“The motivation for this new research was to do a similarly designed study with longer-term follow-up,” Benjamin Smith, MD, assistant professor in the department of radiation therapy at The University of Texas MD Anderson Cancer Center, said in a press release. “We wanted to do a 10-year update, focusing specifically on the mastectomy question. The fundamental reason it was determined that women didn’t need radiation was because the additional therapy did not change mastectomy rates.”

Smith and colleagues identified 7,403 women aged 70 to 79 years who had undergone conservative surgery between 1992 and 2002. They used Medicare claims to determine radiation therapy status and to identify women who underwent mastectomy subsequent to initial treatment.

Exclusion criteria included nonepithelial histology, lobular carcinoma in situ, distant metastasis/unknown stage, no pathologic diagnosis, unknown tumor laterality/bilateral breast cancer, second breast/other cancer diagnosed, or death during treatment interval.

The risk for subsequent mastectomy within 10 years of diagnosis was 3.2% for patients who received radiation therapy vs. 6.3% for patients who did not receive radiation therapy (P<.001), according to study results.

In adjusted analyses, radiation therapy was associated with a lower risk for mastectomy (HR=0.33; 95% CI, 0.22-0.48).

Radiation therapy provided no benefit for patients aged 75 to 79 years without high-grade tumors who had a pathologic lymph node assessment (P=.80). For all other subgroups, radiation therapy was connected with an absolute reduction in risk for mastectomy that ranged from 4.3% to 9.8% at 10 years.

“The national guidelines, while well intended and important, may gloss over the certain nuances needed for making critical decisions with patients,” Smith said. “Our study may shed additional light on some of those nuances and provides data that physicians can use when talking to their patients about whether to go forward with radiation. Personally, having this data point, together with the previous findings, gives me the confidence to not routinely recommend radiation in women age 75 and over with non–high-grade tumors.”

Disclosure: The researchers report no relevant financial disclosures.