The lives of about 400 women with early breast cancer could be saved every year if bisphosphonates were routinely used as adjuvant therapy to prevent recurrence, oncologists say.

But the recommended drugs such as zoledronate are off-patent, unlicensed and currently underused for the prevention of breast cancer recurrence, the MOGA 2019 ASM in Canberra was told.

Dr Isobel Porter a medical oncologist at Royal North Shore Hospital, Sydney, said about 15,000 postmenopausal women with early breast cancer could potentially benefit from bone-modifying drugs that were shown in a 2015 study to reduce the risk of disease recurrence by 14% and reduce mortality by 18%.

She presented findings from a survey of 60 Australian medical oncologists showing that almost all were aware of guidelines such as those from ASCO-CCO, which recommend zoledronic acid (4 mg intravenously every 6 months) be considered as adjuvant therapy for postmenopausal patients with breast cancer who are deemed candidates for adjuvant systemic therapy.

But the survey showed that few of the oncologists were prescribing bone-modifying drugs as adjunctive preventive therapy for eligible breast cancer patients, mostly because of costs issues, since the drugs are neither TGA approved for this indication nor PBS subsidised.

In the survey, 83% of the oncologists said they would prescribe a bone-modifying drug for the adjuvant management of early breast cancer to prevent disease recurrence if they were listed on the PBS. However, while 65% said they were currently prescribing bone modifying drugs for women with early breast cancer, most were doing so for prevention of bone loss, usually after a BMD scan and in combination with vitamin D and calcium.

The survey also showed that the use of bone-modifying drugs for recurrence prevention was rarely discussed at breast cancer multidisciplinary team meetings.

Dr Porter said the situation in Australia resembled that in the UK about five years ago, when only about a quarter of medical oncologists were routinely prescribing bone modifying agents for prevention of disease recurrence in postmenopausal women.

However, a 2019 survey showed that 98.5% of UK oncologists are now implementing the ASCO recommendations. This was in part due to health services being persuaded by a “Sheffield Business Case” showing major cost savings from prevention of secondary cancers and no longer needing to do BMD testing when bone-modifying drugs are used routinely, said Dr Porter.

“We haven’t been ignoring this in Australia and MOGA’s Breast Cancer Expert Group have been working very hard to get this funded, but the difficulty is that pharmaceutical companies do not see a return on these drugs now they are off-patent, so there is a reluctance for them to bring [applications for] these indications to the TGA and the PBAC,” she said.

“These are not fancy, new expensive drugs. Generic bisphosphonates such as zoledronic acid 4mg are available at a cost of $50-200, but there is a postcode lottery in Australia as to whether women with early breast cancer receive bone-modifying drugs have access to them,” noted Dr Porter.

“For example, women in South Australia are able to receive treatment in public hospitals if they’ve got a more than 10% risk of 10-year recurrence of breast cancer – according to the state-wide formulary for high-cost medicines.”

“So perhaps we need to take a different tack. If we can’t convince [authorities] on the humanitarian aspects maybe we should be making the business case, saying that from a financial perspective this is a beneficial thing to be doing … because the costs will be offset by savings from reduced morbidity and mortality from secondary breast cancer and bone loss as well as not having to do the fairly expensive DEXA scans ” she suggested.