LISBON, Portugal ― In patients with advanced metastatic breast cancer, an increase in progression-free survival (PFS) was associated with a better quality of life for a longer period.
The new results come from an analysis of data from the phase 3 PALOMA-2, which investigated the use of palbociclib (Ibrance, Pfizer) plus letrozole (Femara, Novartis) in women with estrogen receptor–positive human epidermal growth factor receptor 2–negative metastatic breast cancer. The main results from this trial show that palbociclib with letrozole improved PFS by 10 months compared to letrozole therapy alone (24.8 months vs 14.5 months).
A new analysis of the data shows that for patients in either treatment arm whose disease took longer to progress, there was a significantly greater delay in the time it took for their health-related quality of life (QoL) to deteriorate compared to patients who had experienced progression earlier. Health-related QoL was maintained for a median of 29 months vs 19 months, reported Nadia Harbeck, MD, PhD, head of the Breast Cancer Center at the University of Munich, Germany.
She was speaking here at the Advanced Breast Cancer Fourth International Consensus Conference (ABC 4).
"The results could imply that delay in progression-free survival could help to delay deterioration of patient-reported quality of life" in this patient population, Dr Harbeck commented.
"This could be of great value to these patients, for whom there are currently no curative therapies," she added.
"Advanced breast cancer is, for the moment, an incurable disease, and, therefore, a balance between quantity and quality of life is of extreme importance to patients," said conference chair Fatima Cardoso, MD, director of the breast unit here at the Champalimaud Clinical Center, in a statement.
Approached for comment, Eric P. Winer, MD, professor of medicine at Harvard Medical School and director of the breast oncology center at Dana-Farber Cancer Institute, Boston, Massachusetts, noted that the new analysis is exploratory.
The findings were not specific to either treatment arm (ie, palbociclib with letrozole vs letrozole alone), he noted. "Essentially, each had the same finding, that QoL was less likely to deteriorate in patients whose disease remained under control."
Although the analysis does not prove that prolongation of PFS in this setting was associated with less of a decrease in QoL or better quality of life, the findings are still "reassuring," he said.
"If you can slow disease progression in MBC [metastatic breast cancer] by palbociclib and endocrine therapy, it is very meaningful for patients, as you can slow deterioration of QoL," Dr Winer said.
He added, "QoL is usually very good at the beginning of the first endocrine-based treatment in MBC, and severe symptoms are rare. Thus, QoL will not be improved substantially by any cancer drug. But if we can help patients to live longer without disease progression, we will be able to help them to maintain a good QoL."
"We've always presumed that PFS had a positive impact on quality of life. This suggests that quality of life is a surrogate for PFS," Dr Winer told Medscape Medical News.
"Tumor progression, as detected by imaging, which is a common endpoint in clinical trials, is very controversial, as it has been unclear how this is reflected in QoL," he continued. "We are now able to show that tumor progression is indeed reflected in QoL. These results underline the importance of this endpoint in trials in MBC. "
In PALOMA-2, patients' quality of life was assessed by administering the Functional Assessment of Cancer Therapy–Breast (FACT-B) questionnaire at baseline and on day 1 of cycle 2, 3, and 5 until progression of disease or the end of treatment.
Overall score was based on combined measures of physical well-being (energy, nausea), social and family well-being (emotional support from friends, family), emotional well-being (anxiety, sadness), functional well-being (sleep, ability to work), and symptoms (shortness of breath, hair loss, pain). A higher score indicated better QoL.
At the time at which data were cut off, patients from each treatment arm were stratified on the basis of disease progression. Time to deterioration of QoL was defined as the length of time for the total FACT-B score to decrease by 7 points from baseline, with no subsequent increase above threshold.
QoL deterioration time was compared between patients who did not have a PFS event and those who did in each of the treatment arms as well as in both arms combined.
Although more treatment-related side effects were seen with targeted therapy, palbociclib was "generally easy-to-tolerate medication," pointed out Dr Winer. He emphasized that the choice of therapy used to achieve PFS in patients with advanced breast cancer is key. "A bone marrow transplant wouldn't be worth it if you're sick as a dog for 6 months."
When it comes to assessing the impact of adverse events on QoL, patient-reported outcomes (PROs) are much more useful than clinicians' grading of toxicity, he added.
The use of PROs is "crucial," agreed Dr Cardosa. "It's much more relevant for the patient than an evaluation of side effects done by physicians or nurses."
Combining clinical assessment of disease progression with PROs instead of considering them mutually exclusive "might be critical," suggested Dr Harbeck in a statement.
"These are the kinds of things that, ultimately, doctors should be thinking about when deciding on treatment," said Dr Winer. "Whether you have cancer or diabetes, survival and quality of life are the two things that matter to all of us. It's about how well and how long you live."
Dr Harbeck has relationships with Lilly, Novartis, and Pfizer. Dr Winer has relationships with Genentech and Lilly.
Advanced Breast Cancer Fourth International Consensus Conference (ABC 4). Abstract OR65, presented November 2, 2017.
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Cite this: Disease Control Prolongs QoL in Advanced Breast Cancer - Medscape - Nov 06, 2017.