Advanced techniques in neoadjuvant radiotherapy allow dose escalation without increased dose to the organs at risk
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an1, 2 · M. Oechsner1 · S. Kampfer1 · T. Schuster3 · M. Molls1 · H. Geinitz1 1 Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich 2 Department of Radiation Oncology, Marienhospital Herne,
Universitätsklinkum der Ruhr-Universität Bochum, Herne 3 Institute of Medical Statistics and Epidemiology, Klinikum rechts
der Isar, Technische Universität München, Munich
Advanced techniques in neoadjuvant radiotherapy allow dose escalation without increased dose to the organs at risk Planning study in esophageal carcinoma
Surgical resection alone is associated with considerably higher R1/R2 resections and/ or a high rate of locoregional failure for the treatment of locally advanced esophageal carcinoma (LAEC [1, 2]); thus, it is not an optimal treatment option for LAEC. Several studies have reported improvement in outcomes of surgery after neoadjuvant treatment. Walsh et al. [3] showed a significantly higher overall survival rate after neoadjuvant radiochemotherapy (RCT) for LAEC in a prospective randomized trial. Gebski et al. [2] confirmed these results in a meta-analysis including 10 random ized comparisons of neoadjuvant RCT versus surgery alone (n=1,209). Neoadjuvant RCT resulted in a significant survival benefit of 13% at 2 years. Although prospective trials and meta-analyses do not show any survival benefit of the trimodality therapy (neoadjuvant RCT followed by surgery) compared to RCT alone [4, 5], a better local control after trimodality therapy justifies its administration in medically and technically (potentially) operable patients. In the trimodality treatment, radiotherapy (RT) usually consists of a conventional or conformal three-dimensional treatment plan with 40–50.4 Gy at 1.8– 2.0 Gy per fraction. Nevertheless, local infield recurrence remains the main reason of treatment failure after all treatment modalities [6, 7, 8].
Another challenging, not uncommon situation for the radiation oncologist is that surgical resection is not possible or the patient rejects surgical intervention after restaging and/or re-evaluation at 4–6 weeks after RCT. Considering that the tumor cells have been treated with an insufficient radiation dose, they might repopulate during the break for re-evaluation and impede long-term disease control or cure. Theoretically, a higher radiation dose is associated with a higher cell kill rate and results in better local control and prevents tumor cell displacement during surgery. If doses could be delivered in a curative range, cancellation of surgical resection would be less fatal and the mandatory curative surgical resection would theoretically be an optional procedure for patients with complete response. However, employing higher radiation doses to treat esophageal cancer is handicapped through the limited tolerance dose of organs at risk (OAR), such as the heart, spinal cord, the lungs, and of course the esophagus itself. Several studies report a higher morbidity and mortality after higher radiation doses [9, 10, 11]. Of note, most of the
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