Nathan López Bezerra
A recent clinical trial suggests that taking a daily vitamin D supplement during chemotherapy may improve the chances of completely eliminating breast cancer tumors before surgery.
The study, published in a peer-reviewed journal, enrolled 80 women aged 45 and older who were diagnosed with breast cancer and about to begin neoadjuvant chemotherapy, which is chemotherapy given before surgery to shrink tumors. The participants were randomly assigned to take either 2,000 international units of vitamin D each day or a placebo for six months while they received their chemotherapy treatment.
Vitamin D is known for its role in bone health, but it also affects immune function and cellular processes related to cancer. Breast tissue has vitamin D receptors. When these receptors are activated, they can slow tumor growth and promote the death of cancer cells.
After completing chemotherapy and surgery, 43 percent of the women who took vitamin D had a pathological complete response. That means no cancer was detected in their breast tissue. In the placebo group, only 24 percent achieved that result. That is nearly double the rate of tumor eradication before surgery.
The researchers also measured blood levels of vitamin D in the participants. Women with vitamin D levels above 20 nanograms per milliliter were more than three times as likely to reach a complete tumor response, regardless of other clinical factors. This finding indicates that even having moderate vitamin D levels can potentially improve the effectiveness of chemotherapy.
Vitamin D works by influencing genes that control cell growth, programmed cell death, and the spread of tumors. It can also make cancer cells more sensitive to common chemotherapy drugs such as anthracyclines and taxanes. Earlier research has shown that vitamin D increases cancer cell sensitivity to these drugs and strengthens their tumor-killing effects.
Many breast cancer patients, especially women after menopause, have low vitamin D levels at the time of diagnosis. That deficiency may weaken their response to treatment. Chemotherapy itself can lower vitamin D levels because patients spend less time in the sun and the treatment affects the body’s metabolism. That makes supplementation during treatment a reasonable strategy.
The study was relatively small and was conducted at a single center. Still, its randomized design adds to the evidence that taking a safe, accessible dose of vitamin D during chemotherapy may be a simple way to improve outcomes. More research is needed to confirm these findings in larger and more diverse groups and to find the best dose.
Because vitamin D supplements are affordable and safe at recommended doses, they could be a practical addition to breast cancer care for patients who have low levels. The takeaway from this research is that maintaining adequate vitamin D may help chemotherapy work better.
