“I’m Cancer Free. Can I Quit Now?”

Craig R. Hildreth, MD

Former President Jimmy Carter, who was diagnosed with metastatic malignant melanoma earlier this year, announced last week that after receiving radiation therapy to four brain metastases a follow-up scan revealed that they were gone. In addition to the stereotactic radiation to the brain he has undergone resection of a liver metastasis and is actively receiving the immune checkpoint inhibitor pembrolizumab every 3 weeks. Several headlines described Carter as being “cancer free,” a choice of words that must be interpreted with caution.

Medical oncologists interviewed for news stories were prudent to remind us that a complete response to treatment, especially for malignant melanoma, is not the same as being cured of the cancer. Given the emotional volatility associated with this diagnosis I would not be surprised if many people jumped to the conclusion that melanoma is now a curable malignancy. This would be a disservice to reality and to those patients who will not get as good a result from treatment.

If we examine data from the pivotal trial comparing pembrolizumab with another checkpoint inhibitor, ipilimumab, we see that the overall response rate for every 3 week pembrolizumab (President Carter’s schedule) was 32.9%, the complete response rate was 6.1%, and the 1-year survival was 68.4%.[1] Although two out of every three patients on this every 3 week schedule had visceral (internal organ) metastases, only 9.7% had brain metastases. Did they do as well as the others?

What makes President Carter’s presentation unique is the surgical removal of a liver metastasis. With the complete remission obtained after brain radiation, he now has no measurable disease, which places him in an extremely favorable status. Not only that, a recent review of 551 of patients undergoing liver resection of metastatic melanoma showed the average survival to be 2 years, with 24% of patients alive 5 years later.[2] Not every patient is so fortunate to be in this group.

Given Mr. Carter’s age and the increasing effectiveness of immunotherapy in prolonging survival in metastatic melanoma, he may very well live out the rest of his life without a recurrence, and hooray for that. Now for the fine print: the annual cost of just the drug alone (for a 70 kg patient on pembrolizumab every 3 weeks) is $153,000. At least it is well tolerated by the majority of patients.

How wonderful to be able to say that you are cancer free, and if you’re an optimist you won’t worry much about what tomorrow will bring. Just don’t forget to show up for your next infusion, and the next one, and the next one…

References:

1. Robert C, Schachter J, Long GV, et al. Pembrolizumab versus Ipilimumab in Advanced Melanoma. N Engl J Med. 2015;372:2521–2532.

2. Hameed AM, Ng EE, Johnston E, et al. Hepatic resection for metastatic melanoma: a systematic review. Melanoma Res. 2014;24:1–10.