Study compares survival with early-stage breast cancer treatments

Breast-conserving surgery plus radiation was associated with better disease-specific survival than mastectomy alone in patients with early-stage breast cancer, according to a new study.

Researchers performed a large, population-based study to determine whether breast-conserving surgery plus radiation or mastectomy alone yielded similar outcomes in patients with early breast cancer outside randomized clinical trials. They also examined whether survival rates differed according to patient age and hormone-receptor (HR) status.

Data were obtained from the California Cancer Registry on women who were diagnosed with stage I or stage II breast cancer between 1990 and 2004 and who underwent breast-conserving surgery or mastectomy. Vital status was followed through 2009, with a median follow-up of 110.6 months. The researchers used Cox proportional hazards modeling to compare overall and disease-specific survival in those who received each type of therapy, and analyses were stratified by age (<50 years or ≥50 years) and tumor HR status. The study results were published online Jan. 28 by Cancer.

Overall, 112,154 women were eligible for the study. Of these, 61,771 (55%) opted for lumpectomy and radiation and 50,383 (45%) had mastectomy without radiation. Those who had breast-conserving surgery plus radiation had better overall and disease-specific survival compared with those who had mastectomy alone (adjusted hazard ratio for overall survival in the entire cohort, 0.81; 95% CI, 0.80 to 0.83).

Kaplan-Meier survival estimates indicated that survival benefit was greater with breast-conserving surgery in both younger and older women and in those with both HR-positive and HR-negative disease. In Cox multivariable analysis, women 50 years of age and older who had HR-positive disease had the largest benefit from breast-conserving surgery over mastectomy, while younger women with HR-negative disease had the smallest benefit (hazard ratios, 0.86 [95% CI, 0.82 to 0.91] vs. 0.88 [95% CI, 0.79 to 0.98]).

The authors noted that their study was limited by its population-based design and that the California Cancer Registry did not collect data on variables such as comorbid conditions and patient and clinician preferences. They also noted that data on radiation therapy in particular may have been incomplete.

However, they concluded that breast-conserving surgery plus radiation was associated with improved disease-specific survival versus mastectomy without radiation among patients with early disease. “These findings support the notion that [breast-conserving therapy], when combined with radiation, confers at least equivalent and perhaps even superior survival to mastectomy as definitive breast cancer treatment,” they wrote.