People who are uninsured or covered by Medicaid are more likely to be diagnosed with cancer later than those with private insurance, according to a review of more than 3 million cancer cases.
The cancers most likely to be diagnosed at a more advanced stage in this population were those that could be detected by screening or symptom assessment by a physician, according to the study.
Uninsured or Medicaid-covered patients were twice as likely to be diagnosed with stage III colorectal cancer as patients with private insurance, and 1.6 times more likely to be diagnosed with stage IV colorectal cancer, wrote Dr. Michael T. Halpern and colleagues, from the American Cancer Society, Atlanta.
The 5-year survival rate for colon cancer is 93% if it is diagnosed at stage I, 44% if diagnosed at stage IIIC, and only 8% if diagnosed at stage IV (Lancet Oncol. 2008 Feb. 18 [doi:10.1016/s1470–2045(08)70032–9]).
The review used information from the U.S. National Cancer Database, a hospital-based registry that collects information from 1,430 facilities, and included information from 3,742,407 patients diagnosed between 1998 and 2004. The database captures about 75% of all cancer cases diagnosed in the United States, Dr. Halpern and colleagues said.
The review included patients with 12 cancers: breast, colorectal, lung, prostate, urinary bladder, non-Hodgkin's lymphoma, uterus, kidney, melanoma, pancreas, thyroid, and ovary.
Uninsured patients had a significantly increased likelihood of presenting with stage II, III, or IV cancer at diagnosis, compared with insured patients. The largest odds ratio for diagnosis at stage II, compared with stage I disease was for colorectal cancer (odds ratio 1.9). For diagnosis at stage III or stage IV, compared with stage I, the largest odds ratio was for breast cancer (OR 2.9). In comparison to privately insured patients, the study found Medicaid patients had an increased risk of presenting with stage II vs. stage I disease for 6 of the 12 cancers, and with stage III or IV vs. stage I disease for 11 of the 12 cancers.
In comparison to whites, blacks were more likely to be diagnosed at stage III or stage IV for 10 of the 12 cancers regardless of insurance status.
Hispanic patients were more likely to present with more advanced-stage disease at diagnosis than were white patients. Odds ratios for presenting with more advanced-stage disease were generally lower for Hispanics than for black patients.
Because the findings of later diagnosis were found across all the types of cancer that can be detected early with screening or prompt medical attention, “These findings have important implications for screening programmes and access to medical care,” Dr. Halpern and colleagues wrote.