Sunshine vitamin, calcium may help avert bone loss associated with AIs

Supplementation with vitamin D, otherwise called sunshine vitamin, and calcium may help women with breast cancer protect against bone loss associated with aromatase inhibitors (AIs), suggests a 5-year follow-up study from Brazil.

At 5 years, there were no differences in bone mineral density (BMD) outcomes between women with hormone receptor-positive cancers treated with AIs and those with triple-negative or HER-2 positive cancers treated with another therapy.

All women were examined at three timepoints – before the start of therapy, at 6 months, and 5 years. Those with vitamin D levels below 30 ng/mL received 7,000 IU daily for 8 weeks, followed by 1,000 IU daily as a maintenance dose. [SABCS 2021, abstract P1-13-04]

Women with osteopenia were administered calcium carbonate 500 mg. Those with osteoporosis received zoledronic acid 4 mg.

There were 140 patients (average age, 65 years) in both groups, the majority of them were vitamin D deficient at baseline.

Significant decline in BMD loss

At 6 months and at 5 years, both groups had significant declines in BMD loss at the femoral neck and femur, with no significant difference between groups. Similarly, there was no significant difference in bone density loss in the spine between groups.

“Vitamin D deficiency is high in the general population, especially in postmenopausal breast cancer patients. Therefore, vitamin D and calcium supplementation have an impact on these women’s lives,” said lead author Dr Marcelo Antonini from the Hospital Servidor Publico Estadual in São Paulo, Brazil.

Vitamin D helps regulate calcium and phosphorus absorption and supports bone health, he pointed out. Despite the encouraging results, larger studies must be carried out on vitamin D supplementation in breast cancer patients, Antonini said. “This was not the case in noncancer patients as the benefits of vitamin D and calcium supplementation were already well established in this patient group.”

Protective against arthralgia

AIs massively reduce circulating oestrogens in postmenopausal women, an effect that is decisive for survival and reduction of tumour relapse but is also associated with adverse events and quality of life problems, including those targeted to the musculoskeletal system.

Early last year, one study has shown that vitamin D supplementation is protective for arthralgia in breast cancer patients undergoing AI treatment. [Rev Osteoporos Metab Miner 2021;13:66-71]

Patients with baseline serum 25 (OH) D (25-hydroxyvitamin D) levels <30 ng/mL received oral calcifediol 16,000 IU every 2 weeks. Arthralgia and bone loss related to AIs were assessed at 3 months and 1 year of follow-up.

At 3 months, women who achieved vitamin D 40 ng/mL or higher were less likely to have joint pain (p<0.05). At 1 year, for every 10 ng/mL increase in serum vitamin D at 3 months, there was a reduction in lumbar spine bone loss (adjusted β=0.177 percent; p<0.05).

“AI-induced joint pain is vitamin D-dependent, and that 40 ng/mL is the effective target threshold for serum 25 (OH) D levels to reduce the risk of both joint pain incidence and its worsening,” said the study authors.