Chemotherapy is tough on the body. But for many women with breast cancer, it can play an important role before surgery — helping shrink tumors and, in some cases, making less extensive surgery possible.
This approach is called neoadjuvant chemotherapy, which means chemotherapy is given before surgery to remove a tumor. Research has shown it can help some women become eligible for breast-conserving surgery instead of mastectomy, especially in more aggressive forms of breast cancer.
But researchers are also looking for ways to help more women have an even stronger response to treatment.
In breast cancer studies, one important measure is called a pathological complete response. That means that after chemotherapy, no invasive cancer is found in the breast tissue or lymph nodes removed during surgery.
It doesn’t mean a person is automatically cured. But it is an encouraging sign — and it’s one researchers want to see more often.
Now, a small randomized clinical trial suggests a simple, low-cost nutrient may help improve that response in some women undergoing chemotherapy for breast cancer: vitamin D.
Vitamin D and chemotherapy response
Researchers at São Paulo State University in Brazil studied 80 women over age 45 who had breast cancer and were eligible to begin neoadjuvant chemotherapy.
The women were divided into two groups. One group took 2,000 IU of vitamin D3 daily, while the other received a placebo. All of the women underwent chemotherapy at the same time.
After six months of cancer treatment and supplementation, the researchers found that 43% of the women taking vitamin D had a pathological complete response, compared with 24% of women in the placebo group.
In other words, the women taking vitamin D were more likely to have no detectable invasive cancer in tissue removed during surgery.
That’s an encouraging finding. But it’s also important to keep it in perspective: This was a small study, and larger trials are needed before vitamin D can be considered a standard add-on to breast cancer treatment.
“Even with a small sample of participants, it was possible to observe a significant difference in the response to chemotherapy,” says Eduardo Carvalho-Pessoa, president of the São Paulo Regional Brazilian Society of Mastology and one of the study authors.
He also noted that the dose used in the study — 2,000 IU per day — was far lower than the high-dose regimens sometimes used to correct vitamin D deficiency.
Many participants started with low vitamin D
One reason the results are especially interesting is that many of the women in the study had low vitamin D levels at the start.
Vitamin D is best known for its role in helping the body absorb calcium and phosphorus, making it essential for strong bones. But it also plays a role in immune function and inflammation — two areas that may matter during cancer treatment.
In the study, vitamin D levels increased in the women who received supplementation during chemotherapy.
“With supplementation, levels increased throughout chemotherapy treatment, which reinforces a possible contribution to the patients’ recovery,” Carvalho-Pessoa told Agência FAPESP.
He also pointed out that vitamin D is inexpensive and widely available compared with some medications used to improve chemotherapy response.
But that does not mean women undergoing cancer treatment should start vitamin D on their own.
Why patients should talk to their oncology team first
Supplements can seem harmless, especially when they’re common and inexpensive. But during cancer treatment, even familiar vitamins can matter.
Some supplements may interfere with treatment, affect lab values or interact with medications.
That’s why anyone being treated for breast cancer should talk with their oncologist before starting vitamin D or any supplement.
A doctor can test vitamin D levels, review medications and determine whether supplementation is appropriate — and at what dose.
More research is needed
The study authors say the results justify a larger round of research to better understand vitamin D’s role in chemotherapy response.
“These are encouraging results that justify a new round of studies with a larger number of participants,” Carvalho-Pessoa says. “This will allow a greater understanding of the role of vitamin D in increasing the response to chemotherapy treatment and, consequently, in the greater likelihood of breast cancer remission.”
Previous research has also linked healthy vitamin D levels with lower breast cancer risk. One study found that women with vitamin D levels of 60 ng/mL or higher were less likely to develop breast cancer than women with levels below 20 ng/mL.
Still, prevention studies and treatment-response studies answer different questions. This new trial suggests that vitamin D may help support chemotherapy response in some women — especially those who begin treatment with low levels.
The bottom line
Vitamin D is not a cancer treatment. And it should never be used in place of chemotherapy, surgery, radiation or other treatments recommended by an oncology team.
But this small clinical trial suggests that checking and correcting low vitamin D levels may be worth discussing with a doctor before or during breast cancer treatment.
Sources:
Vitamin D increases the likelihood that breast cancer will disappear with chemotherapy — Agência FAPESP
Vitamin D Supplementation Improves Pathological Complete Response in Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy: A Randomized Clinical Trial — Nutrition and Cancer
New Study: Chemo Before Surgery Avoids Need for Mastectomy for Many with Triple-Negative Breast Cancer — Dana-Farber Cancer Institute
Chemotherapy is as effective before breast cancer surgery as after — MedicalXpress
In Certain Cancers, Giving Chemotherapy Preoperatively May Result in a Survival Advantage — Center for Restorative Breast Surgery
FAQ: Vitamin D and Chemotherapy Response
A small randomized clinical trial found that women with breast cancer who took vitamin D during neoadjuvant chemotherapy were more likely to have a pathological complete response than women who took a placebo. Because the study was small, more research is needed before vitamin D can be considered part of standard breast cancer treatment.
A pathological complete response means that after treatment, no invasive cancer is found in the breast tissue or lymph nodes removed during surgery. It is an encouraging sign, but it does not mean a person is automatically cured.
Cancer patients should not start vitamin D — or any supplement — during chemotherapy without talking to their oncology team first. Supplements can affect treatment, medications, lab results or calcium levels, depending on the person and the dose.
Vitamin D supports bone health, immune function and inflammation control. In the study, many participants started with low vitamin D levels, and supplementation helped raise those levels during chemotherapy. Researchers believe this may have contributed to better treatment response.
Patients with questions about vitamin D can ask whether their vitamin D level should be tested, whether they are low or deficient and whether supplementation is safe with their treatment plan.