Environmental Cancer Risks: What Oncologists Want You To Know

Mikkael Sekeres, a hematologist-oncologist, recently encountered a patient with leukemia who was taking antioxidant supplements “to boost my immune system.” The patient’s proactive inquiry – whether the supplements were safe to grab alongside her prescribed medications – highlighted a widespread, and often undisclosed, practice among cancer patients.

An estimated 64 to 81 percent of individuals diagnosed with cancer utilize dietary supplements, according to Sekeres. Nearly half of those patients do not inform their healthcare providers about their supplement use. This practice extends beyond those currently battling the disease; approximately 50 percent of the general population reports taking supplements, many with the intention of cancer prevention.

However, the efficacy and safety of these supplements remain largely unproven. Unlike prescription drugs and over-the-counter medications, dietary supplements are subject to significantly less stringent regulation by the Food and Drug Administration (FDA). While supplement manufacturers are required to submit a premarket safety notification asserting their products “will reasonably be expected to be safe” when used as directed, the FDA’s intervention is typically reactive, occurring only after safety concerns arise post-market. Crucially, there is no requirement to demonstrate that a supplement actually works.

The lack of rigorous testing raises concerns, particularly as research increasingly points to environmental factors as potential cancer risks. A recent Washington Post report detailed growing awareness of environmental cancer risks, ranging from air pollution and microplastics to natural radiation. Simultaneously, another Washington Post investigation suggests a possible link between rising cancer rates among millennials and factors such as ultra-processed foods and exposure to various chemicals.

Sekeres’s experience underscores a broader challenge in cancer care: the need for open communication between patients and their doctors regarding all substances being ingested, and a critical evaluation of the scientific evidence supporting the use of supplements. The oncologist’s concern is amplified by the fact that supplements are not consistently tested in clinical trials, leaving a significant gap in understanding their true impact on cancer treatment and prevention.

A Washington Post Live event in December 2025 explored the evolving landscape of cancer treatment, focusing on the roles of science, technology, and prevention. The discussion highlighted the complex interplay of factors influencing cancer care, but did not specifically address the role of supplements.