Avastin fails to Prevent Colon Cancer recurrence

Genentech has released preliminary results on the use of Avastin in adjuvant therapy of colon cancer. The treatment failed. (Adjuvant treatment is given to selected patients, generally Dukes 3 colon cancer, after complete resection in hopes of preventing recurrence) Details will be presented at the ASCO meetings in May.

The article in the NY Times notes:

“The existing chemotherapy already keeps about 70 percent of colon cancer patients free of the disease three years after their surgery.”

However, it’s not correct to state that current treatment keeps 70% of people free of cancer. If people who receive treatment were compared to those who did not, the benefit would be about 10%. That is, the recurrence rate would be around 40% for those not treated and 30% for those receiving treatment. That means 30% will recur no matter what we do and 60% wouldn’t recur (in the time period) without therapy.

This article notes the limited efficacy of treatment vs placebo.

“1526 patients with resected B (56%) and C (44%) carcinoma of the colon were enrolled and 1493 were confirmed as eligible. 736 were assigned to the treatment group and 757 to the control group. Fluorouracil/folinic acid significantly reduced mortality by 22% (95% CI 3-38; p = 0.029) and events by 35% (22-46; p < 0.0001), increasing 3-year event-free survival from 62% to 71% and overall survival from 78% to 83%. Compliance with treatment was good; more than 80% of patients completed the planned treatment.”

More recent regimens don’t appear to do much better:

“Oxaliplatin has significant activity when combined with 5-FU-leucovorin in patients with metastatic colorectal cancer. In the 2,246 patients with resected stage II or stage III colon cancer in the MOSAIC study, the toxic effects and efficacy of FOLFOX4 were compared with the same 5-FU-leucovorin regimen without oxaliplatin administered for 6 months.[27] The preliminary results of the study with 37 months of follow-up demonstrated a significant improvement in DFS at 3 years (77.8% vs. 72.9%, P = .01) in favor of FOLFOX4. When reported, there was no difference in overall survival.”

I don’t want to imply that treatment is completely ineffective as some people do not recur after therapy. It is however inefficient in that the great majority of patients receive no benefit.

Using a very expensive drug such as Avastin ($50-100,000 for a course of therapy) for this indication should lead to concerns about cost efficiency and the cost of a QALY (Quality Adjusted life Year). In this case the drug failed but drug companies view adjuvant use as one of the most profitable, and I don’t necessarily mean beneficial, areas and will continue trials.

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