For primary care doctors, screening for cancer is like relying on a few streetlights to search an expanse of darkness.
The average American is currently recommended to have regular screenings for just three types of cancer: breast, colorectal, and cervical. Screening increases the chances that a cancer will be caught in its earliest stages, when the chance of a cure is higher. If caught early, most cancers are localized and can be surgically removed or radiated.
An unfortunate reality is that people of color tend to be diagnosed with many cancers at later stages, and their chance of surviving is lower across the board. Black people with cancer have a 28 percent higher chance of dying from it than white people do. The mortality rate for breast cancer, the most common cancer in American women, is nearly 40 percent higher for Hispanic and Black women than for their white counterparts. The mortality rate for prostate cancer, the most common cancer in American men, is two to three times higher in the Black community. A similar pattern also shows up with colorectal cancer, with poor people and people of color generally being diagnosed at a later stage.
There are many reasons for these later diagnoses: reduced access to health care, lower rate of cancer screenings, and a lack of health insurance or paid medical leave. The result is that even among people with the same type of cancer treated at the same hospital, with the same insurance status, income, and education level, patients of color still have a lower chance of survival.
Regrettably, Black, Hispanic, and other people of color have historically been underrepresented in clinical trials relating to cancer, including ones aimed at determining the value of more aggressive screening and early detection. In 1993, Congress passed the National Institutes of Health (NIH) Revitalization Act to increase the inclusion of women and minorities in clinical trials, but only 2 percent of NIH-funded trials over the next 20 years met this goal. And this exclusion from research trials may affect clinical recommendations.
For example, Black men were underrepresented in prostate cancer screening trials that concluded there was little benefit to screening all adult American males. The recommendations to doctors that were developed as a result of those trials, which drastically reduced prostate cancer screening, may have been disproportionately detrimental to Black men. In the largest clinical trial on screening for lung cancer, which kills more Americans than any other cancer, only 9 percent of the study subjects were of any diverse racial group, although nonwhite people made up 28 percent of the US population in 2011, the year of the trial.
We especially need to improve early cancer detection. Routine medical visits, including those for cancer screening, steeply declined in 2020 because of COVID-19, and now we’re seeing more late-stage diagnoses as a result of missed screenings. For example, in the early months of the pandemic, 7 percent of breast cancer diagnoses in the Kaiser Permanente health care system were made at a late stage, compared with 2 percent in 2019. People of color, who already suffer from reduced access to primary care, will be disproportionately represented among those with cancer diagnoses that might have been caught with regular screening.
Fortunately, there are new technologies on the horizon that may help fill the gaps. Scientists and startup companies are developing “liquid biopsies” — blood tests that detect molecular signals of dozens of cancers at once. If a patient tested positive, doctors could follow up with imaging or tissue biopsies to confirm a specific cancer diagnosis.
These simple blood tests would be offered at doctor’s offices and community clinics, in theory making them more convenient and quicker for patients who have historically faced obstacles to health care access. There is hope that liquid biopsies may provide a practical safety net for individuals who often fall through the cracks in the status quo, in which cancer screening can require multiple time-consuming and sometimes invasive tests such as a colonoscopy, a mammogram, or a CT scan.
That’s why special effort must be taken to include representative samples of all racial and ethnic groups in clinical trials on these technologies. And if these tests pass muster and are someday recommended as standard screens, it will be vital both to bring these technologies to community hospitals that serve populations of color and to ensure their affordability.
However, initial studies on liquid biopsies appear to have been underrepresentative. My analysis of the first few large trials indicates that between 4.6 and 13 percent of the study subjects were people of color — less than half their proportion in the general population.
A commitment to diversity in upcoming clinical trials for liquid biopsies could determine whether this cutting-edge early detection technology will widen or close the gap in cancer outcomes that has persisted for too long.
Dr. Sana Raoof is a resident physician in radiation oncology at Memorial Sloan Kettering Cancer Center.