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Table 1 Characteristics of the patients.

From: Modeling the effect of age in T1-2 breast cancer using the SEER database

Characteristics of patients Total No. % of all cases Total N(0) % of all cases Total N(+) % of all cases
Patient number 83804 100.0% 58139 69.4% 25665 30.6%
SEER area:       
East (Connecticut, Detroit, Atlanta) 31795 37.9% 21683 25.9% 10112 12.1%
Central (Iowa, New Mexico, Utah) 20459 24.4% 14202 16.9% 6257 7.5%
West (San Francisco-Oakland, Hawaii, Seattle) 31550 37.6% 22254 26.6% 9296 11.1%
Year of diagnosis:       
1988–89 15390 18.4% 10424 12.4% 4966 5.9%
1990–91 16660 19.9% 11589 13.8% 5071 6.1%
1992–93 17042 20.3% 11894 14.2% 5148 6.1%
1994–95 17072 20.4% 11897 14.2% 5175 6.2%
1996–97 17640 21.0% 12335 14.7% 5305 6.3%
Age at diagnosis (years):       
20–39 5869 7.0% 3396 4.1% 2473 3.0%
40–49 16231 19.4% 10262 12.2% 5969 7.1%
50–59 18051 21.5% 12362 14.8% 5689 6.8%
60–69 20703 24.7% 15110 18.0% 5593 6.7%
70–79 17161 20.5% 12802 15.3% 4359 5.2%
80+ 5789 6.9% 4207 5.0% 1582 1.9%
Race:       
White and Other 78025 93.1% 54572 65.1% 23453 28.0%
Black 5779 6.9% 3567 4.3% 2212 2.6%
Marital status at diagnosis:       
Single, widowed, other 33224 39.6% 23171 27.6% 10053 12.0%
Married 50580 60.4% 34968 41.7% 15612 18.6%
Topography:       
Inner quadrant 12537 15.0% 9726 11.6% 2811 3.4%
Others 71267 85.0% 48413 57.8% 22854 27.3%
Histology:       
Ductal 64370 76.8% 43924 52.4% 20446 24.4%
Others 19434 23.2% 14215 17.0% 5219 6.2%
Grade:       
Poor/undifferentiated 25161 30.0% 15265 18.2% 9896 11.8%
Others 58643 70.0% 42874 51.2% 15769 18.8%
ER/PR status (+ includes unspecified):       
ER+ and PR+ 63306 75.5% 44332 52.9% 18974 22.6%
ER+ and PR- 7001 8.4% 4852 5.8% 2149 2.6%
ER- and PR+ 2554 3.0% 1696 2.0% 858 1.0%
ER- and PR- 10943 13.1% 7259 8.7% 3684 4.4%
Tumor size (mm) (T stage):       
< = 5 (T1a) 3349 4.0% 3069 3.7% 280 0.3%
> 5 and < = 10 (T1b) 16997 20.3% 14691 17.5% 2306 2.8%
> 10 and < = 20 (T1c) 36754 43.9% 26443 31.6% 10311 12.3%
> 20 and < = 50 (T2) 26704 31.9% 13936 16.6% 12768 15.2%
Number of nodes examined:       
1–9 14225 17.0% 10525 12.6% 3700 4.4%
10–14 27004 32.2% 19210 22.9% 7794 9.3%
15–19 23102 27.6% 15820 18.9% 7282 8.7%
20+ 19473 23.2% 12584 15.0% 6889 8.2%
Number of nodes involved:       
0 58139 69.4% 58139 69.4% 0 0.0%
1–3 16778 20.0% 0 0.0% 16778 20.0%
4+ 8887 10.6% 0 0.0% 8887 10.6%
Breast conserving surgery/Radiotherapy       
no/no 46862 55.9% 31752 37.9% 15110 18.0%
no/yes 3972 4.7% 1024 1.2% 2948 3.5%
yes/no 4438 5.3% 2946 3.5% 1492 1.8%
yes/yes 28532 34.0% 22417 26.7% 6115 7.3%
  1. ER = estrogen receptor, N(0) = node negative, N(+) = node positive, PR = progesterone receptor, SEER = Surveillance, Epidemiology, and End Results Program.