What Tumor Complexity Can Teach Us About Who Gets Left Out of Precision Medicine
In my school's biology research program, I study the breast cancer microbiome — how microbial signals and immune cells interact within breast tumors, using computational analysis of genomic and spatial data to see whether those interactions influence immune response and treatment outcomes. The deeper I get into this work, the more it becomes clear that no two tumors are alike. Two patients with the same diagnosis can have completely different microenvironments — different immune cell populations, different microbial signals, different molecular subtypes — which is exactly why "precision medicine" exists: treatment tailored to the specific biology of a specific tumor, not a one-size-fits-all protocol.
But precision only helps the people who can access it. And access to precision medicine is not evenly distributed. Genomic testing and personalized treatment depend on infrastructure — sequencing capacity, specialists who can interpret results, insurance willing to cover a test that costs far more than a standard one — and that infrastructure clusters in well-resourced hospitals and well-insured patients. Socioeconomic status, geography, and healthcare infrastructure all shape who actually gets access to genomic testing, which means the same biological insight that could extend one patient's life may never reach another.
The disparity shows up in outcomes, too, not just access. Research on breast cancer has found that Black women with residual estrogen receptor-positive disease after neoadjuvant chemotherapy have worse distant recurrence-free survival than white women — a gap that researchers link in part to a more pro-metastatic tumor microenvironment. That's a finding at the intersection of biology and inequity: the tumor itself may behave differently depending on factors tied to broader health disparities, and then the treatment system layers unequal access on top of that.
This is the uncomfortable truth about precision medicine as it exists right now: the more precisely we can tailor treatment to biology, the more precisely we can also see — and sometimes reproduce — who gets left out. Better science alone doesn't close that gap. It has to be paired with policy that gets genomic testing, specialists, and follow-up care to the patients who currently can't reach them, not just the ones whose zip code or insurance plan happens to make it easy.