Table 2.

Effect of Chemotherapy on Mortality in Women With Node-Positive Operable Breast Cancer Diagnosed in 1992–1996 in SEER Areas

Age Group	Total No. of Patients (% of Patients Receiving Chemotherapy)	Risk (Cox Proportional HR and 95% CI)*
		HR	95% CI
65–69 y	1440 (53.5)	0.70	0.57–0.88
70–74 y	1590 (36.1)	0.87	0.70–1.07
75–79 y	1275 (20.1)	1.06	0.84–1.34
80–84 y	753 (10.4)	0.90	0.63–1.29
≥85 y	406 (2.7)	1.21	0.53–2.74
All women aged ≥65	5464 (30.9)	0.90	0.80–1.01

^*Cases who received chemotherapy vs those who did not. Cox proportional HR was adjusted for age (continuous), ethnicity (white, black, other), marital status (married, unmarried, unknown), tumor stage (II, IIIA), tumor size (<1, 1–<2, 2–<3, 3–<4, ≥4 cm, or unknown), hormone receptor status (positive, negative, or unknown), tumor grade (well, moderately or poorly differentiated, or undetermined), number of positive lymph nodes (1, 2–4, 5–9, 10–43, and positive nodes but unknown number), comorbidity index scores (0, 1, 2, or 3+), 11 SEER areas, other treatment (breast-conserving surgery alone, breast-conserving surgery plus radiotherapy, mastectomy alone, or mastectomy with radiation), and census tract household income in quartiles (four categories plus unknown one), and year of diagnosis (continuous).

SEER = The National Cancer Institute's Surveillance, Epidemiology, and End Results cancer registry; HR = hazard ratio; CI = confidence interval.