Last weekend, I participated in a debate on the question of whether people who had undergone a resection of a node-negative early stage non-small cell lung cancer (NSCLC) should ever be candidates for adjuvant (post-operative) chemotherapy. I had been assigned the side of there being a role for adjuvant therapy “sometimes”, as opposed to “never”. Besides the truism that always and never are very rarely the right answer in medicine (can’t say these are never the right answer), I also had been assigned an easier task because I would say that the evidence does favor the concept that there aren’t ironclad rules about which patients are better served by pursuing adjuvant chemotherapy and which ones may well do better without it.
The basic principle is this: we know that people who undergo surgery for lung cancer remain at some risk for the cancer recurring. The stage of the cancer provides a pretty good approximation of the prognosis, which is really primarily the likelihood of the cancer recurring and the patient dying from the cancer. The lower the stage (from Ia on the low end to IVb on the high end), the better the prognosis. In the world of resectable, curable NSCLC, patients who have stage II or IIIa NSCLC are the group of surgery patients who have the strongest evidence to support additional therapy after surgery, and the results are much more equivocal for patients with stage Ib NSCLC (in the slightly outdated staging system that was used in these trials, these were primarily people with a cancer larger than 3 cm or with a smaller one but pleural lining involved by tumor, and no lymph nodes involved).
Chemotherapy, typically 3-4 cycles of a platinum-based doublet combination, has been shown to reduce the risk of the cancer recurring, thereby improving survival, in higher risk patients. How much of a benefit it provides depends on how great the risk is that the cancer will recur: it is relative to the risk of recurrence. What this means is that for people with a very high risk of recurrence, like 50-75% with surgery alone, that reduction in absolute terms may be pretty substantial, in the range of a 20% reduction. In contrast, if a person has a very low risk of recurrence, such as 10% for a very small and well-behaved cancer, the absolute reduction might be more like 1-2%. In contrast, the detrimental effect of chemotherapy, in terms of both acute challenges and potential long-term risks, are the same whether someone has a more threatening or a less threatening cancer. The detrimental effects are more related to the health of the patient.
