Zip Code-Related Income Disparities in Patients With Colorectal Cancer

Screening and early detection reduce morbidity and mortality in colorectal cancer. Our aim is to study the effect of income disparities on the clinical characteristics of patients with colorectal cancer in Massachusetts.

Patients were extracted from a database containing all surgically treated colorectal cancers between 2004 and 2015 at a tertiary hospital in Massachusetts. We split patients into 2 groups: "above-median income" and "below-median income" according to the median income of Massachusetts ($74,167).

The analysis included 817 patients. The above-median income group consisted of 528 patients (65%) and the below-median income group consisted of 289 patients (35%). The mean age of presentation was 64 ± 15 years for the above-median income group and 67 ± 15 years for the below-median income group (P = .04). Patients with below-median income were screened less often (P < .001) and presented more frequently with metastatic disease (P = .02). Patients with above-median income survived an estimated 15 months longer than those with below-median income (P < .001). The survival distribution was statistically significantly different between the groups for stage III disease (P = .004), but not stages I, II, or IV (P = 1, 1, and .2, respectively). For stage III disease, a lower proportion of below-median income patients received chemotherapy (61% vs. 79%, P = .002) and a higher proportion underwent nonelective surgery (5% vs. 2%, P = .007).

In Massachusetts, patients with colorectal cancer residing in lower income areas are screened less, received adjuvant chemotherapy less, and have worse outcomes, especially when analyzing those who present with stage III disease.