K Jerzak1, N Dudalski2, K Pritchard3, P Sun4, S A Narod5. 1. Department of Medicine, University of Toronto, Toronto. 2. McMaster University, Hamilton. 3. Department of Medicine, Sunnybrook Odette Cancer Centre, Toronto;; Dalla Lana School of Public Health, University of Toronto, Toronto; and. 4. Women's College Research Institute, Women's College Hospital, Toronto, ON. 5. Dalla Lana School of Public Health, University of Toronto, Toronto; and; Women's College Research Institute, Women's College Hospital, Toronto, ON.
Abstract
BACKGROUND: Women with small nonpalpable breast tumours have an excellent prognosis. The benefit of radiotherapy in this group of low-risk women is unknown. METHODS: A cohort of 1595 women with stages i-iii invasive breast cancer treated with breast-conserving surgery were followed for local recurrence. Using t-tests, baseline demographic data and tumour characteristics were compared for the women who had palpable (n = 1023) and mammography-detected (n = 572) breast cancers. The 15-year actuarial risk of local recurrence was estimated using a Kaplan-Meier method, stratified for adjuvant radiation therapy (yes or no), tumour palpability (palpable or not), and tumour size (≤1 cm or >1 cm). Hazard ratios (hrs) and 95% confidence intervals (95% cis) were calculated using a multivariate Cox regression model. Results were considered statistically significant if 2-tailed p values were less than 0.05. RESULTS: Among women with a nonpalpable tumour, the 15-year actuarial rates of local recurrence were, respectively, 13.9% and 18.3% for those treated and not treated with adjuvant radiation therapy (hr: 0.65; 95%ci: 0.40 to 1.06; p = 0.08). Among women with small nonpalpable breast cancers (≤1.0 cm), the rates were 14.6% and 13.4% respectively (p = 0.67). The absolute reduction in 15-year local recurrence was 11.0% for women with palpable tumours. CONCLUSIONS: Our results suggest that women with small (<1 cm) screen-detected nonpalpable breast cancers likely derive little benefit from adjuvant radiotherapy; however, an adequately powered randomized trial would be required to make definitive conclusions.
BACKGROUND:Women with small nonpalpable breast tumours have an excellent prognosis. The benefit of radiotherapy in this group of low-risk women is unknown. METHODS: A cohort of 1595 women with stages i-iii invasive breast cancer treated with breast-conserving surgery were followed for local recurrence. Using t-tests, baseline demographic data and tumour characteristics were compared for the women who had palpable (n = 1023) and mammography-detected (n = 572) breast cancers. The 15-year actuarial risk of local recurrence was estimated using a Kaplan-Meier method, stratified for adjuvant radiation therapy (yes or no), tumour palpability (palpable or not), and tumour size (≤1 cm or >1 cm). Hazard ratios (hrs) and 95% confidence intervals (95% cis) were calculated using a multivariate Cox regression model. Results were considered statistically significant if 2-tailed p values were less than 0.05. RESULTS: Among women with a nonpalpable tumour, the 15-year actuarial rates of local recurrence were, respectively, 13.9% and 18.3% for those treated and not treated with adjuvant radiation therapy (hr: 0.65; 95%ci: 0.40 to 1.06; p = 0.08). Among women with small nonpalpable breast cancers (≤1.0 cm), the rates were 14.6% and 13.4% respectively (p = 0.67). The absolute reduction in 15-year local recurrence was 11.0% for women with palpable tumours. CONCLUSIONS: Our results suggest that women with small (<1 cm) screen-detected nonpalpable breast cancers likely derive little benefit from adjuvant radiotherapy; however, an adequately powered randomized trial would be required to make definitive conclusions.
Entities:
Keywords:
Breast cancer; palpable breast tumours; radiation therapy
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