The Role of Definitive Chemoradiotherapy – How to Avoid the Knife — ASN Events

The Role of Definitive Chemoradiotherapy – How to Avoid the Knife (#55)

Rebecca Wong 1
  1. Radiation Oncology, Princess Margaret Cancer Center, University Health Network, University of Toronto, Toronto, Ontario, Canada

Chemoradiotherapy (CRT), whether delivered as neoadjuvant therapy with planned surgery, or as definitive therapy alone is virtually identical in terms of dose fractionation and treatment volumes in most contemporary practice settings. The questions of whether surgery is necessary in all patients following neoadjuvant CRT, how to make this selection, and the incremental value it is expected to provide are key towards individualized care.

 Two randomized trials in patients with squamous cell carcinoma compared CRT with or without subsequent surgery using an equivalence design. Both concluded there were no survival differences irrespective of whether surgery was added. Local control was superior at the price of greater toxicity in the surgical group however. Especially for patients where the most important outcome is survival, and the relative importance placed on local control is secondary, CRT alone, reserving surgery as salvage represent a sound treatment option for patients with squamous cell carcinoma. For patients with adenocarcinoma, only indirect evidence is available at this time to guide treatment individualization. Trimodality studies have consistently demonstrated superior survival outcome for complete and near complete responders. Subgroup analysis by histology would suggest the effect of neoadjuvant therapies is not different across histologies. Early PET response is emerging as one of the most promising strategy to identify patients who are destined to achieve a complete response and enjoy a favorable outcome following CRT. Other prognostic factors such as biological markers and tumor size response are emerging. In patients with a favorable biological profile, especially where the tradeoff between toxicity and benefit is delicate, clinical complete response could provide a path towards deferring surgery without any compromise in survival.