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Prophylactic radiation to prevent brain metastases from breast cancer does not appear to cause cognitive decline, presented at San Antonio Breast Cancer Symposium.

Treating patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer with prophylactic cranial irradiation as a procedure to prevent brain metastases show no indication that the treatment produces cognitive dysfunction any greater than other women who did not have the radiotherapy, researchers said here at the 33rd annual San Antonio Breast Cancer Symposium (SABCS).

"About 30% to 35% of women with HER2-positive metastatic breast cancer develop brain metastases," said Peter Canney, MD, Beatson West of Scotland Cancer Centre, Glasgow, United Kingdom. "Development of brain metastases severely affects patients' quality of life in many ways so it is one of the conditions we want to avoid in these women who are dealing with a difficult disease."

In the study, women were randomised to either radiation or no radiation if they had been diagnosed with HER2-positive breast cancer and also had been diagnosed with progressive systemic disease and had trastuzumab therapy plus chemotherapy as planned treatment.

Patients underwent screening with magnetic resonance imaging or computer-assisted tomography of the brain after randomisation to exclude patients with subclinical central nervous system disease.

Dr. Canney said patients underwent neurocognitive function at baseline and again at 3, 6, and 9 months following randomisation using various psychological studies to assess quality of life, anxiety, depression, and cognition. Patients who were randomised to receive radiation received a dose of 30 Gy in 10 fractions.

Using the Addenbrooke's Cognitive Examination, the median score for the 13 women randomly assigned to undergo prophylactic cranial irradiation was about 2, virtually the same as the 17 women who did not opt for irradiation in the prospective study (P =.805), said Dr. Canney at his poster presentation on December 11.

Although there was no overall survival difference at 2 years in his small study (P =.867), the risk of experiencing brain metastases was numerically higher among those women who did not have prophylactic radiation. Seven of these women experienced brain metastases compared with 3 women who underwent cranial radiation (P =.18).

None of the scores on the tests of quality of life, depression, or anxiety achieved statistical significance at any time point, Dr. Canney reported.

"Among the problems this devastating complication causes is that in the United Kingdom, and many other countries, the development of brain metastases immediately means that a woman is no longer allowed to drive," he explained. "So instead of being able to live a relatively normal life and go about with activities of daily living, she become virtually homebound, dependent on others, and her quality of life plummets."

Dr. Canney and colleagues began recruiting women to determine what impact, if any, prophylactic cranial irradiation, had on a woman's cognitive functioning. "Various authors have reported a relatively high incidence of central nervous system metastases in patients with HER2-positive tumours who are receiving trastuzumab-based therapy for metastatic breast cancer," he said. "There has been concern with regard to the possible neuropsychological sequelae of radiation, although data from 2 prospective randomised trials assessing toxicity and quality of life after radiation for small-cell lung cancer have failed to confirm this."

Despite lack of evidence that radiation adversely affects cognition, Dr. Canney said he had difficulty recruiting women for the study because their doctors recommended against the procedure due to concerns of negative impact on cognition. "We have had to close our study because of lack of enrolment," he said.

Dr. Canney said he was hoping to find other researchers with truncated series of patients to include in the trials in hopes that more patients would add power to their findings and perhaps attain statistical significance.

Source: DG News