Age-related variations in the use of axillary dissection in breast cancer: a comparative analysis of clinical outcomes in women treated with vs without axillary dissection
P. Truong a, V. Bernstein a, B. Chua a, C. Speers a and I.A. Olivotto a
[a] Radiation Therapy and Systemic Therapy Programs, Breast Cancer Outcomes Unit, British Columbia Cancer Agency, Vancouver Island Cancer Centre, University of BC, Victoria, BC, Canada
Purpose: Axillary dissection (AD) provides staging information and guides adjuvant treatment for patients with breast cancer. The impact of AD on breast cancer survival is unclear. This study examines age-related variations in the use of AD and analyzes survival in women with T1-T2 breast cancer according to age and AD use.
Materials and Methods: Data from the Breast Cancer Outcomes Unit database was analyzed for 7,134 women aged 50+ referred to the British Columbia Cancer Agency from 1989–1998 with invasive T1-T2, M0 breast cancer. Primary tumor characteristics and systemic therapy use were compared using chi-square tests for women who were treated with vs without AD (AD+ vs AD-) according to three age groups: 50–64, 65–74, and 75+.
Five-year actuarial breast cancer specific and overall survival were calculated using life table analysis. Comparisons of survival between AD+ vs AD- patients were performed using Wilcoxon statistics.
Results: Among 7,134 women, 47% (n=3,329) were aged 50–64, 34% (n=2,434) were aged 65–74, and 19% (n=1,371) were aged 75+. AD was performed in 91% (n=6,485) of all patients. AD was omitted more frequently with advancing age (4% vs 9% vs 22% in women aged 50–64, 65–74 and 75+ respectively, p<.001). Tumor Characteristics in AD- vs AD+ Patients: Among women aged 50–64, AD- and AD+ patients had similar distributions of T2 tumors (29% vs 35%, P=.21) and grade III disease (33% vs 37%, P=.20). Among women in the older age groups, AD- patients had fewer T2 tumors (age 65–74: 20% T2 vs 32% T2, p<.001 and age 75+: 27% T2 vs 40% T2, p<.001) and were less likely to have grade III disease (age 65–74: 21% gIII vs 32% gIII, p<.001 and age 75+: 18% gIII vs 27% gIII, P=.001). Lymphovascular invasion was found less frequently in AD- patients: (age 50–64: 25% vs 35%, P=.03, age 65–74: 16% vs 32%, p<.001, and age 75+: 24% vs 30%, P=.04). Estrogen receptor positivity was similar between AD- and AD+ patients (age 50–64: 82% vs 76%, P=.18, age 65–74: 85% vs 81%, P=.11, and age 75+: 88% vs 86%, P=.29).
Systemic Therapy Use: Overall, 42% did not receive any systemic therapy, 42% received Tamoxifen only, 7% received chemotherapy only, and 8% received both Tamoxifen and chemotherapy. The proportions of AD- and AD+ patients who received systemic therapy were: age 50–64: 53% vs 60%, P=.36, age 65–74: 57% vs 56%, P=.73, and age 75+: 57% vs 54%, P=.32.
Clinical Outcome: Five-year actuarial breast cancer specific survival and overall survival according to age and AD use are summarized in Table 1. Actuarial breast cancer specific survival was lower in AD- women aged 65–74 (82% vs 88%, P=.04) but was similar in AD- and AD+ women aged 50–64 and 75+. Actuarial overall survival was lower in AD- vs AD+ women in all three age groups: age 50–64: 80% vs 86%, P=.06, age 65–74: 68% vs 82%, P=.0004, and age 75+: 60% vs 68%, P=.03.
Conclusion: Axillary dissection was more frequently omitted with advancing age. The omission of AD did not impact breast cancer specific survival in women aged 50–64 or aged 75+ but was associated with lower breast cancer specific survival in women aged 65–74 despite similar rates of systemic therapy use.
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