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Survival is better after lumpectomy than mastectomy in early breast cancer, US study shows

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f577 (Published 29 January 2013) Cite this as: BMJ 2013;346:f577
  1. Susan Mayor
  1. 1London

Women with early stage breast cancer who are treated with lumpectomy and radiotherapy have significantly better survival than women who have a mastectomy, a retrospective study of US data has found.1

Researchers analyzed data in the California cancer registry from all 112 154 women in the state who had been given a diagnosis of early stage, invasive breast cancer between 1990 and 2004 and who were treated with either lumpectomy and radiotherapy or mastectomy and were followed to December 2009. Just over half (55%) had breast conserving therapy, and the remainder had mastectomy without radiation.

“Despite randomized trials suggesting that breast conserving surgery and mastectomy result in equivalent overall survival, recent studies have shown increased rates of mastectomy for subgroups of patients, including younger women with early stage tumors,” said Shelley Hwang, professor of surgery at Duke University Medical Center, Durham, North Carolina, and the study’s lead author.

A likely cause is a perception that women with unfavorable factors, including younger age and estrogen receptor negative disease, may have worse outcomes after lumpectomy. So the research group set out to see whether the equivalent outcomes after lumpectomy and mastectomy seen in randomized trials were achieved in the general population and whether any subgroups did worse with one type of surgery than the other.

Unexpectedly, the results showed better overall survival at three years in women who underwent lumpectomy for early breast cancer than in those who had a mastectomy, with a 19% lower risk of dying from any cause (hazard ratio 0.81 (95% confidence interval 0.8 to 0.83)). This benefit was seen even after data were adjusted for size and grade of tumor, number of positive nodes, race, socioeconomic status, and age at diagnosis. The authors were not able to adjust for whether diagnosis followed routine breast screening.

As well as better overall survival, long term breast cancer specific survival was equivalent or better in women who underwent lumpectomy, irrespective of age or hormone receptor status. The greatest benefit was seen in women aged 50 years or over with estrogen receptor positive breast cancer (hazard ratio 0.86 (0.82 to 0.91)), but all subgroups showed at least equivalent outcomes, with the exception of women with the largest tumors (4-5 cm).

Further analysis showed that women who underwent mastectomy had a higher risk of dying from heart disease and other conditions in the three years after their surgery for breast cancer than those treated with lumpectomy. This may indicate that they had more comorbidities at the time of the diagnosis of breast cancer, which the researchers said may have influenced surgical decision making. But they said, “This factor alone cannot explain why women undergoing mastectomy had lower disease specific survival after adjusting for age and tumor characteristics.”

Hwang said, “Our findings have important implications for understanding the overall benefit of breast conserving surgery at the population level. These results provide confidence in the efficacy of breast conserving surgery even among younger patients with hormone receptor negative disease, who were thought to be at relatively higher risk of local recurrence.”

Notes

Cite this as: BMJ 2013;346:f577

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