Table 1.
Baseline characteristics associated with receipt of IMRT among patients with anal squamous cell cancer treated with chemoradiation therapy in SEER-Medicare database
| Characteristic | n | % treated with IMRT | P value* |
|---|---|---|---|
| Entire cohort | 1165 | 39.3 | |
| Age at diagnosis | .32 | ||
| ≤65 y | 318 | 43.1 | |
| 66–70 y | 292 | 39.4 | |
| 71–75 y | 229 | 35.4 | |
| >75 y | 326 | 38.3 | |
| Sex | .005 | ||
| Male | 414 | 44.7 | |
| Female | 751 | 36.4 | |
| Race | .0005 | ||
| White | 1037 | 38.0 | |
| Nonwhite† | 128 | 50.0 | |
| Marital status | .05 | ||
| Married | 401 | 35.9 | |
| Single‡ | 713 | 40.3 | |
| Unknown | 51 | 52.9 | |
| Comorbidity index | .03 | ||
| 0 | 643 | 37.2 | |
| 1 | 213 | 36.6 | |
| ≥2 | 309 | 45.6 | |
| Disability status | .78 | ||
| Good | 1078 | 39.4 | |
| Poor | 87 | 37.9 | |
| HIV | .06 | ||
| Yes | 95 | 48.4 | |
| No | 1070 | 38.5 | |
| SEER historic stage | .50 | ||
| Local | 650 | 38.2 | |
| Regional | 424 | 41.5 | |
| Unknown | 91 | 37.4 | |
| AJCC T category | .52 | ||
| T1 | 192 | 41.7 | |
| T2 | 401 | 39.9 | |
| T3 | 165 | 42.4 | |
| T4 | 71 | 32.4 | |
| Unknown or no primary identified | 336 | 37.2 | |
| AJCC N category | .06 | ||
| N0 | 826 | 39.0 | |
| N1 | 64 | 50.0 | |
| N2 | 107 | 43.0 | |
| N3 | 53 | 45.3 | |
| Unknown | 115 | 29.6 | |
| AJCC composite stage | .41 | ||
| I | 156 | 41.0 | |
| II | 409 | 38.6 | |
| III | 273 | 42.9 | |
| Unknown | 327 | 36.4 | |
| Year of diagnosis | <.0001 | ||
| 2001–2003§ | 208 | 5.3 | |
| 2004 or 2005 | 214 | 12.1 | |
| 2006 or 2007 | 213 | 32.4 | |
| 2008 or 2009 | 256 | 54.7 | |
| 2010 or 2011 | 274 | 77.4 | |
| SEER registry∥ | <.0001 | ||
| Northeast | 149 | 22.1 | |
| Midwest | 102 | 32.4 | |
| South | 343 | 34.1 | |
| West | 571 | 48.2 | |
| Chemotherapy | .05 | ||
| Mitomycin based | 878 | 41.0 | |
| Cisplatin based | 128 | 29.7 | |
| Neither mitomycin nor cisplatin based | 159 | 37.7 | |
| PET scan at diagnosis | <.0001 | ||
| Yes | 483 | 62.5 | |
| No | 682 | 22.9 | |
| Dual eligible | .69 | ||
| Yes | 318 | 40.3 | |
| No | 847 | 39.0 | |
| SES composite¶ | .12 | ||
| First quartile (lowest)† | 354 | 37.0 | |
| Second quartile | 282 | 44.3 | |
| Third quartile | 273 | 35.5 | |
| Fourth quartile (highest) | 256 | 41.0 | |
| Rural-urban classification | .1 | ||
| Metropolitan | 984 | 40.3 | |
| Urban or rural | 181 | 33.7 | |
| HSA radiation oncologist density | .0009 | ||
| First quartile (lowest)† | 365 | 31.5 | |
| Second quartile | 283 | 45.6 | |
| Third quartile | 271 | 42.8 | |
| Fourth quartile (highest) | 246 | 39.8 | |
| Radiation treatment center | .0004 | ||
| Freestanding center | 392 | 46.4 | |
| Hospital-based outpatient center | 773 | 35.7 | |
| NCI-Designated Cancer Center | .0003 | ||
| Yes | 58 | 62.1 | |
| No | 1107 | 38.1 | |
| Residency program | .5 | ||
| Yes | 482 | 38.2 | |
| No | 683 | 40.1 | |
| Provider experience with IMRT | <.0001 | ||
| Upper half (>3.4 patients/y) | 601 | 50.4 | |
| Lower half | 564 | 27.5 |
Abbreviations: AJCC = American Joint Committee on Cancer; HIV = human immunodeficiency virus; HSA = Health Service Area; IMRT = intensitymodulatedradiationtherapy;NCI = NationalCancer Institute; PET = positron emission tomography; SEER = Surveillance, Epidemiology, and End Results; SES = socioeconomic status.
P values are based on the Pearson χ2 test.
Patients in whom this characteristic was deemed unknown are included in this category for privacy purposes because of the low number of patients.
Single includes unmarried, divorced, separated, and widowed.
The 2001–2003 categories are combined in this table for privacy purposes because of the low number of IMRT patients.
West comprises the San Francisco, Hawaii, New Mexico, Seattle, Utah, San Jose, Los Angeles, and Greater California Registries; Midwest comprises the Detroit and Iowa Registries; Northeast comprises the Connecticut and New Jersey Registries; and South comprises the Atlantic, Rural Georgia, Kentucky, Louisiana, and Greater Georgia Registries.
A composite measure for area SES is presented based on the following variables from the 2000 US Census data: median household income, percentage of persons aged ≥25 years with at least a high school education, and percentage of persons living below the poverty level.