Diagnoses spike in people's 65th year when most Americans become newly eligible for Medicare coverage.
Cancer is a disease associated with aging so incidence and mortality statistics generally climb as people get older.
But in a study published in Cancer this week, Stanford researchers showed that there is a large spike at age 65 in the diagnoses of lung and other common cancer that suggests a “Medicare effect” of insurance coverage above and beyond any natural history of the disease.
“Essentially, we showed there is a big jump in cancer diagnoses as people turn 65 and are thus Medicare eligible,” said Joseph B. Shrager, M.D., the study’s senior author and a professor of cardiothoracic surgery at Stanford School of Medicine, in a press release about the study.
Their findings could be relevant to proposals mooted by the Biden administration and Congressional Democrats to lower the age of Medicare eligibility from 65 to 60.
Using data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) program, Shrager and his colleagues computed the relative percent increase in diagnoses from one age year to the next, a novel statistic they dubbed age-over-age (AoA) that is analogous to the year-over-year growth calculations used in business. They found that lung cancer diagnoses increased by 3% to 4% from one year to the next as people turned 61, 62, 63 and 64. When they turned 65, the rate doubled and increase was especially pronounced in the diagnoses of stage 1 lung cancer. And, as the table below shows, in the years after 65th year spike, the AoA for lung cancer dips.
Their results show a similar pattern for colon, breast and prostate cancer; in fact it was even more pronounced in colon cancer with 21% AoA increase in stage 1 diagnoses at age 65 and 33% increase in stage 2 diagnoses.
The Stanford researchers also compared uninsured patients, ages 61 to 64, to those ages 65 to 69 when Medicare coverage is nearly universal. That comparison yielded two findings. First, a stage shift toward earlier diagnoses in the “post-Medicare” group. Second, a longer five-year median survival time from diagnosis to death in that group (4.0 months for the pre-Medicare group versus 7.0 months in the post-Medicare group). Again, the pattern was similar for the other cancers, although the pre- and post-Medicare differences in survival time were quite a bit greater for the other cancers.
The researchers mention the advent of lung cancer screening as perhaps being a factor in the spike in stage 1 diagnoses during people’s 65th year. They wrote: “Although lung cancer screening has low penetrance to date, it is possible that a slight increase in computed tomography-based screening, plus the fact that a chest radiogram is frequently ordered when a current/former smoker establishes care with a new physician at the age of 65 years, accounts for the rise in stage 1 lung cancer diagnoses.”
Some of the limitations of the study discussed by Shrager and his colleagues include the lack of granularity about insurance coverage in the SEER database — it doesn’t specify whether people have Part B coverage or not — and their inability to identify the specific subset of Medicare who were uninsured before 65.
Their main takeaway: Their findings are evidence for the effect of healthcare insurance and, specifically, of Medicare coverage, on when people get diagnosed and treated for lung and other cancers. “All of this,” they wrote in their conclusion, “provides support for the hypothesis that patients are delaying cancer-related diagnostic and therapeutic interventions until they become Medicare-eligible.”