Older women with early stage breast cancer are able to tolerate higher intensities of adjuvant chemotherapy protocols than previously thought, Australian research suggests.

Among women over 65, almost two thirds were able to maintain an optimal relative dose intensity (RDI ), clinicians in three Queensland centres have found.

But older women still had high rates of treatment-related toxicities, highlighting the need for early supportive measures including wider use of secondary G-CSF prophylaxis, according to medical oncologists at the Princess Alexandra Hospital, Brisbane.

In a retrospective analysis of 281 women over 65 diagnosed with early stage breast cancer (ESBC) between 2010 and 2015, an optimal RDI (>85%) for chemotherapy was achieved in 63% of patients. An RDI of 100% was achieved by 43% of the women. The median age of the women was 68 years of age and 36% were over the age of 70.

The most common chemotherapy regimens used included adriamycin/cyclophosphamide-weekly paclitaxel (38%), docetaxel/cyclophosphamide (23%) and 5-fluorouracil/epirubicin/ cyclophosphamide-docetaxel (17%). Treatment related toxicities were common, with high rates of hospital admissions (46%) and febrile neutropenia (22%).

The study authors said under-utilisation of adjuvant chemotherapy was one of the key factors behind the poor outcomes for older women with breast cancer. Clinician caution about toxicities with first and second generation chemotherapy regimens often led to dose reductions and delays in adjuvant treatment, but this did not need to be the case with newer therapies, they said.

They noted that a large proportion of the women in their cohort had been treated with second and third generation anthracycline and taxane-based chemotherapy regimens.

Another factor in achieving optimal RDI was the use of primary and secondary GCSF in order to minimise rates of treatment related febrile neutropenia. However PBS criteria limited the use of G-CSF in secondary prophylaxis, the study authors noted.

Nevertheless, they said the prognostic importance of maintaining optimal RDI should encourage clinicians to minimise dose reductions in elderly patients.

“Appropriate geriatric assessment and use of supportive measures such as G-CSF could better assist select groups [ of women] to maintain optimal dose intensity,” they concluded.

The findings are published in Clinical Breast Cancer.