This transcript has been edited for clarity.
Our group, the QUASAR Group, made a very significant contribution in terms of trials and knowledge in this field. One of the things that we still need to discuss and think about in our wider community is the impact of adjuvant chemotherapy in older patients.
Colorectal cancer is a disease of the elderly, with the median age of presentation around 72. We know that, at presentation, more than 50% of patients are aged 65 or over and one third of patients are 75 or over. It’s a disease predominantly of the elderly. Are we justified in giving combination chemotherapy with oxaliplatin to high-risk resected colorectal cancer patients?
There’s a very nice report of a meta-analysis by Dottorini and colleagues that came out recently in the Journal of Clinical Oncology. It’s an excellent group. They did their meta-analytical work according to a strict, rational protocol. Their statistical analyses were on point, and they collected data from all the relevant trials.
According to the results of their study, it could be concluded that the addition of oxaliplatin to adjuvant therapy for resected high-risk colorectal cancer in older patients — patients older than 70 — doesn’t result in any statistically significant gain in terms of preventing recurrences or saving lives.
When we did our QUASAR trials, initially we were looking at control vs fluoropyrimidine chemotherapy. Although there was an overall impact on survival of the whole trial group (the 5000 patients in our study), when we looked by decile, there was a significant diminution of benefit even to fluoropyrimidine therapy in our trial in patients aged 70 or above. I think this careful meta-analysis must make us question the use of oxaliplatin in elderly patients.
What could the explanation be? Why could the well-known and described benefits of oxaliplatin, particularly for stage III disease, attenuate in older people? It may be to do with reduction in dose intensity. Older people have more side effects; therefore, the chemotherapy isn’t completed as planned. Although, increasingly these days, we tend only to be giving 3 months of treatment.
Is there something biologically in terms of the biology or the somatic mutational landscape of the tumor in older people? I don’t think so. Certainly, in terms of their capacity, in terms of stem cell reserve to be as resistant to the side effects of chemotherapy as younger people, we know that does attenuate with age.
Food for thought: The majority of patients I see in the clinic for the adjuvant treatment are elderly. The majority are coming these days with high-risk stage II or stage III disease. There is a real question mark about whether we should be using oxaliplatin at all.
Clearly, one would say that we need more trials of chemotherapy in older folk to see if the addition of drugs like oxaliplatin to a fluoropyrimidine backbone really does make a difference. I’ve said many times before that we, the medical community recommending adjuvant treatment, need to have better risk stratifiers. We need to have better prognostic markers. We need to have better indices that would allow us to perhaps consider these combination treatments in a more focused group of patients who may have a higher risk for recurrence.
Have a look at the paper and see what you think. I think it’s well done. It’s certainly given me pause for thought about the treatment that we will offer our elderly patients.
Have a think about it. Let me know if there are any comments that you’d like to make. For the time being, over and out.
Dr. Kerr is Professor, Nuffield Department of Clinical Laboratory Science, University of Oxford; Professor of Cancer Medicine, Oxford Cancer Centre, Oxford, United Kingdom. He disclosed ties with Celleron Therapeutics, Oxford Cancer Biomarkers, Afrox, GlaxoSmithKline, Bayer HealthCare Pharmaceuticals, Genomic Health, Merck Serono, and Roche.
A version of this article appeared on Medscape.com.