老年肺癌治療: AVAiL (AVAstin in Lung Cancer) trial 合併化療 效果..??

Questions about Benefit from Avastin in Older Patients

Published April 26, 2012 | By Dr West  A group of investigators at Dana Farber Cancer Institute in Boston, MA recently published a very newsworthy article in the Journal of the American Medical Association (JAMA) that argues that patients with advanced non-small cell lung cancer (NSCLC) who are over 65 don't appear to benefit from the addition of Avastin (bevacizumab) to standard chemotherapy with carboplatin/Taxol (paclitaxel).  Several years ago, Avastin was demonstrated in the ECOG 4599 trial to lead to a survival benefit when it was added to carbo/Taxol in Avastin-eligible patients, who are a pretty limited subgroup with a good performance status, no brain metastases (a requirement since relaxed with more experience), no significant hemoptysis, and non-squamous NSCLC histology.  However, there have always been elements of the story that have cast some doubt as to how much benefit it really offers, particularly in older patients.  A subset analysis of the ECOG 4599 trial showed that patients over 70 experience disproportionately greater side effects and complications from Avastin and no survival benefit.   Meanwhile, another large randomized phase III trial called AVAiL (AVAstin in Lung cancer) that was conducted in Europe showed a statistically significant but overall very unimpressive improvement in response rate and progression-free survival when Avastin was added to a different standard chemotherapy backbone of cisplatin and gemcitabine, and this study demonstrated no benefit at all in survival.  Since Avastin was approved by the US FDA in October of 2006, it has been considered a standard of care but not clearly the standard of care, and only about 20-25% of patients in real world clinics actually get it.  The reason it ends up being given to only a minority of patients is a somewhat open question, but in truth, I think that when you disqualify patients with many of the clearer contraindications and then also factor in some relative contraindications such as a cancer next to major blood vessels or a poorly differentiated cancer that is suspected may be of squamous histology, the actual proportion of patients who are really strong candidates for it is probably below 40%.  And then, there is also the question of how much stock clinicians place in the ECOG trial vs. the AVAiL trial that failed to show a benefit…and the fact that the median age of newly diagnosed lung cancer in the US is now around 71 meaning that a very significant fraction of patients with advanced NSCLC are in an age range where the value of Avastin is quite questionable.