Table 1.
Baseline characteristics for entire cohort and by radiation treatment group
| Entire cohort | No. of patients (%)
|
P value* | |||
|---|---|---|---|---|---|
| All patients (N=35,947) | Lumpectomy alone (n=8254) | EBRT (n=26,383) | Brachy (n=1310) | ||
| Patient factors | |||||
| Age | |||||
| 66–69 y | 8129 (22.6) | 887 (10.8) | 6898 (26.2) | 344 (26.3) | <.001 |
| 70–74 y | 9446 (26.3) | 1288 (15.6) | 7792 (29.5) | 366 (27.9) | |
| 75–79 y | 8577 (23.9) | 1631 (19.8) | 6627 (25.1) | 319 (24.4) | |
| ≥80 y | 9795 (27.3) | 4448 (53.9) | 5066 (19.2) | 281 (21.5) | |
| Race | |||||
| White | 32,089 (89.3) | 7332 (88.8) | 23,555 (89.3) | 1202 (91.8) | .01 |
| Black | 2089 (5.8) | 516 (6.3) | 1509 (5.7) | 64 (4.9) | |
| Other/unknown | 1769 (4.9) | 406 (4.9) | 1319 (5.0) | 44 (3.4) | |
| Charlson Comorbidity score | |||||
| 0 | 23,587 (65.6) | 4795 (58.1) | 17,924 (67.9) | 868 (66.3) | <.001 |
| 1 | 7941 (22.1) | 2024 (24.5) | 5615 (21.3) | 302 (23.1) | |
| ≥2 | 4419 (12.3) | 1435 (17.4) | 2844 (10.8) | 140 (10.7) | |
| Year of diagnosis | |||||
| 2002 | 5959 (16.6) | 1374 (16.7) | 4540 (17.2) | 45 (3.4) | <.001 |
| 2003 | 5942 (16.5) | 1259 (15.3) | 4581 (17.4) | 102 (7.8) | |
| 2004 | 6166 (17.2) | 1410 (17.1) | 4585 (17.4) | 171 (13.1) | |
| 2005 | 6049 (16.8) | 1469 (17.8) | 4331 (16.4) | 249 (19.0) | |
| 2006 | 5981 (16.6) | 1391 (16.9) | 4250 (16.1) | 340 (26.0) | |
| 2007 | 5850 (16.3) | 1351 (16.4) | 4096 (15.5) | 403 (30.8) | |
| Tumor factors | |||||
| Behavior | |||||
| Ductal carcinoma in situ | 7229 (20.1) | 2666 (32.3) | 4384 (16.6) | 179 (13.7) | <.001 |
| Invasive carcinoma | 28,718 (79.9) | 5588 (67.7) | 21,999 (83.4) | 1131 (86.3) | |
| Size | |||||
| 0–2.0 cm | 26,429 (73.5) | 5562 (67.4) | 19,758 (74.9) | 1109 (84.7) | <.001 |
| 2.1–5.0 cm | 5945 (16.5) | 1367 (16.6) | 4465 (16.9) | 113 (8.6) | |
| >5 cm | 382 (1.1) | 122 (1.5) | >240 (>0.9) | <11 (<0.9) | |
| Unknown | 3191 (8.9) | 1203 (14.6) | >1890 (>7.1) | <89 (<6.8) | |
| T stage | |||||
| Tis | 7229 (20.1) | 2666 (32.3) | 4384 (16.6) | 179 (13.7) | <.001 |
| T1 | 21,883 (60.9) | 3947 (47.8) | 16,947 (64.2) | 989 (75.5) | |
| T2 | 4912 (13.7) | 1023 (12.4) | 3787 (14.4) | 102 (7.8) | |
| T3 | 247 (0.7) | 71 (0.9) | >160 (>0.6) | <11 (<0.9) | |
| T4 | 831 (2.3) | 301 (3.7) | >510 (>1.9) | <11 (<0.9) | |
| Unknown | 845 (2.4) | 246 (3.0) | 569 (2.2) | 30 (2.3) | |
| Nodal status | |||||
| Pathologic N0 | 20,344 (56.6) | 2445 (29.6) | 16,878 (64.0) | 1021 (77.9) | <.001 |
| Clinical N0 | 4755 (13.2) | 2732 (33.1) | 1935 (7.3) | 88 (6.7) | |
| Pathologic N+ | 4625 (12.9) | 648 (7.9) | 3920 (14.9) | 57 (4.4) | |
| Unknown | 6223 (17.3) | 2429 (29.4) | 3650 (13.83) | 144 (11.0) | |
| Estrogen receptor status | |||||
| Positive | 25,916 (72.1) | 5301 (64.2) | 19,554 (74.1) | 1061 (81.0) | <.001 |
| Negative or borderline | 3958 (11.0) | 634 (7.7) | 3213 (12.2) | 111 (8.5) | |
| Unknown | 6073 (16.9) | 2319 (28.1) | 3616 (13.7) | 138 (10.5) | |
| Grade | |||||
| Low/intermediate grade | 24,137 (67.2) | 5569 (67.5) | 17,588 (66.7) | 980 (74.8) | <.001 |
| High grade | 8620 (24.0) | 1617 (19.6) | 6754 (25.6) | 249 (19.0) | |
| Missing | 3190 (8.9) | 1068 (12.9) | 2041 (7.7) | 81 (6.2) | |
| Extensive intraductal component† | |||||
| No | 28,420 (99.0) | 5541 (99.2) | >21,740 (>98.8) | >1120 (>99.1) | .077 |
| Yes | 298 (1.0) | 47 (0.8) | >230 (>1.0) | <11 (<0.9) | |
| Histology† | |||||
| Invasive ductal, mucinous, or tubular | 21,891 (76.2) | 4255 (76.2) | 16,701 (75.9) | 935 (82.7) | <.001 |
| Invasive lobular | 2361 (8.2) | 430 (7.7) | 1878 (8.5) | 53 (4.7) | |
| Other invasive | 4466 (15.6) | 903 (16.2) | 3420 (15.6) | 143 (12.6) | |
| Overlapping lesion‡ | |||||
| No | 31,787 (88.4) | 6899 (83.6) | 23,696 (89.8) | 1192 (91.0) | <.001 |
| Yes | 4160 (11.6) | 1355 (16.4) | 2687 (10.2) | 118 (9.0) | |
| Laterality | |||||
| Right | 17,611 (49.0) | 3929 (47.6) | 13,021 (49.4) | 661 (50.5) | .01 |
| Left | 18,336 (51.0) | 4325 (52.4) | 13,362 (50.7) | 649 (49.5) | |
| Treatment factors | |||||
| Receipt of chemotherapy | |||||
| No | 31,095 (86.5) | 7888 (95.6) | 22,005 (83.4) | 1202 (91.8) | <.001 |
| Yes | 4852 (13.5) | 366 (4.4) | 4378 (16.6) | 108 (8.2) | |
| Axillary surgery | |||||
| No | 11,533 (32.1) | 5464 (66.2) | 5832 (22.1) | 237 (18.1) | <.001 |
| Yes | 24,414 (67.9) | 2790 (33.8) | 20,551 (77.9) | 1073 (81.9) | |
| Overall patient classification (invasive patients only) | |||||
| ASTRO category† | |||||
| Suitable | 9966 (34.7) | 1175 (21.0) | 8164 (37.1) | 627 (5.4) | <.001 |
| Cautionary | 5059 (17.6) | 446 (8.0) | 4434 (20.2) | 179 (15.8) | |
| Unsuitable | 10,119 (35.2) | 3463 (62.0) | 6506 (29.6) | 150 (13.3) | |
| Unclassified | 3574 (12.5) | 504 (9.0) | 2895 (13.2) | 175 (15.4) | |
| Sociodemographic factors | |||||
| SEER registry | |||||
| Greater California | 12,395 (34.5) | 2953 (35.8) | 8920 (33.8) | 522 (39.9) | <.001 |
| Connecticut | 2965 (8.3) | 683 (8.3) | 2230 (8.5) | 52 (4.0) | |
| Detroit | 2490 (6.9) | 486 (5.9) | 1923 (7.3) | 81 (6.2) | |
| Hawaii | 524 (1.5) | 85 (1.0) | >420 (>1.6) | <11 (<0.9) | |
| Iowa | 2037 (5.7) | 471 (5.7) | >1520 (>5.7) | <28 (<2.1) | |
| New Mexico | 707 (2.0) | 179 (2.2) | 476 (1.8) | 52 (4.0) | |
| Seattle | 2345 (6.5) | 483 (5.9) | 1777 (6.7) | 85 (6.5) | |
| Utah | 851 (2.4) | 198 (2.4) | 603 (2.3) | 50 (3.8) | |
| Rural Georgia | 1228 (3.4) | 289 (3.5) | 812 (3.1) | 127 (9.7) | |
| Kentucky | 2350 (6.5) | 586 (7.1) | 1695 (6.4) | 69 (5.3) | |
| Louisiana | 1859 (5.2) | 418 (5.1) | 1327 (5.0) | 114 (8.7) | |
| New Jersey | 6196 (17.2) | 1423 (17.2) | 4646 (17.6) | 127 (9.7) | |
| Percent of adults in census tract or ZIP code with at least some college education§ | |||||
| 0–7.4 | 9023 (25.1) | 1898 (23.0) | 6727 (25.5) | 398 (30.4) | <.001 |
| 7.5–13.0 | 8956 (24.9) | 2003 (24.2) | 6631 (25.1) | 322 (24.6) | |
| 13.1–21.1 | 8987 (25.0) | 2090 (25.3) | 6599 (25.0) | 298 (22.8) | |
| 21.2–100 | 8981 (25.0) | 2263 (27.4) | 6426 (24.4) | 292 (22.3) | |
| Median income in census tract or | |||||
| ZIP code§ | |||||
| $0–$37,413 | 8990 (25.0) | 2299 (27.9) | 6394 (24.2) | 297 (22.7) | <.001 |
| $37,414–$50,066 | 8987 (25.0) | 2133 (25.8) | 6523 (24.7) | 331 (25.3) | |
| $50,067–$66,720 | 8986 (25.0) | 1932 (23.4) | 6716 (25.5) | 338 (25.8) | |
| $66,721–$200,008 | 8984 (25.0) | 1890 (22.9) | 6750 (25.6) | 344 (26.3) | |
| Urban/rural status | |||||
| Large metropolitan | 21,204 (59.0) | 4859 (58.9) | 15,472 (58.6) | 873 (66.6) | <.001 |
| Metropolitan | 10,377 (28.9) | 2289 (27.7) | 7749 (29.4) | 339 (25.9) | |
| Urban | 1979 (5.5) | 486 (5.9) | 1456 (5.5) | 37 (2.8) | |
| Less urban | 1983 (5.5) | 506 (6.1) | 1432 (5.4) | 45 (3.4) | |
| Rural | 404 (1.1) | 114 (1.4) | 274 (1.0) | 16 (1.2) | |
| Surgeon density in county of residence|| | |||||
| 0–8.3 | 9175 (25.5) | 2115 (25.6) | 6725 (25.5) | 335 (25.6) | <.001 |
| 8.4–11.6 | 8951 (24.9) | 2123 (25.7) | 6436 (24.4) | 392 (30.0) | |
| 11.7–15.4 | 8930 (24.8) | 2065 (25.0) | 6607 (25.0) | 258 (19.7) | |
| ≥15.5 | 8891 (24.7) | 1951 (23.6) | 6615 (25.1) | 325 (24.8) | |
| Radiation oncologist density in county of residence¶ | |||||
| 0–9.0 | 9095 (25.3) | 2232 (27.0) | 6503 (24.7) | 360 (27.5) | <.001 |
| 9.1–14.6 | 8826 (24.6) | 2025 (24.5) | 6419 (24.3) | 382 (29.2) | |
| 14.7–18.8 | 8955 (24.9) | 2051 (24.9) | 6645 (25.2) | 259 (19.8) | |
| ≥18.9 | 9071 (25.2) | 1946 (23.6) | 6816 (25.8) | 309 (23.6) | |
Abbreviations: ASTRO = American Society for Radiation Oncology; Brachy = brachytherapy; EBRT = external beam radiation therapy; SEER = Surveillance, Epidemiology, and End Results.
Cell sizes of less than 11 are reported with limited precision in accordance with the data-use agreement for this dataset. In some cases adjacent cells have also been reported with limited precision to prevent calculation of cell values of less than 11.
*
P value from χ2 test comparing type of treatment (external beam radiation therapy, brachytherapy, or no radiation with covariate).
†
Applies to invasive cases only.
‡
Overlapping lesion refers to the coded site of involvement in the breast and has been used by other groups as a surrogate for multicentricity (2) but is not specific for this clinical-pathologic feature.
§
Fewer than 11 patients had missing values for these variables. Such patients were assumed to have a value for these variables equal to the median population value.
||
Per 100,000 persons.
¶
Per 1,000,000 persons.