Louis B. Harrison

Intraoperative high-dose-rate radiotherapy in the management of locoregionally recurrent head and neck cancer†

The purpose of this article was to present the Beth Israel Medical Center experience using high‐dose‐rate intraoperative radiotherapy (HDR‐IORT) in the management of recurrent head and neck cancer.

Intraoperative Irradiation with Electron-Beam or High-Dose-Rate Brachytherapy

Intraoperative irradiation (IORT) refers to delivery of a single dose of irradiation to a surgically exposed tumor or tumor bed while the normal tissues are protected from the irradiation either by retracting the mobilized tissue or by shielding the anatomically fixed tissues. IORT has traditionally been performed by using an electron beam as the source of irradiation.

Rationale and Historical Perspective of Intraoperative Irradiation

Most of the major advances in clinical applications of radiation therapy in the treatment of cancer have been due to differences in dose distribution between tumor and dose-limiting normal tissue. For most tumor types, the likelihood of obtaining local tumor control improves if irradiation doses delivered to the tumor mass can be safely increased. However, in many clinical situations, the dose which can be delivered safely to the tumor volume is limited by the normal tissues which are in close proximity to the tumor volume.

Recurrent Colorectal Cancer

Aggressive, curative intent treatment approaches in patients with local or regional relapse after resection of primary rectal or colon cancers are often not considered. A growing body of evidence supports an aggressive approach combining external beam irradiation (EBRT) ± chemotherapy, resection, and intraoperative irradiation (IORT) in conjunction with systemic chemotherapy. Data will be presented in this chapter summarizing disease control and survival results with IORT-containing regimens from US and European institutions including the impact of prognostic factors on results and the results in previously irradiated patients. IORT tolerance and future potential as a component of treatment will be discussed.

General Rationale and Historical Perspective of Intraoperative Irradiation

Most of the major advances in clinical applications of radiation therapy in the treatment of cancer have been because of differences in dose distribution between tumor and normal tissue. For most tumor types, the likelihood of achieving local tumor control improves if increasing irradiation doses can be delivered to the tumor mass. However, in many clinical situations, the dose that can be delivered safely to the tumor volume is limited by the normal tissues that are in close proximity to the tumor.

Conclusions and Future Possibilities: IORT

Experience thus far has demonstrated that variable combinations of external beam irradiation (EBRT), intraoperative irradiation (IORT) with electrons (IOERT) or high dose rate brachytherapy (HDR-IORT) and surgical resection are feasible and practical in settings where close interdisciplinary cooperation exists, and that these aggressive approaches appear to impact local control with and without survival. With primary colorectal cancers that are unresectable for cure or for locally recurrent colorectal cancers, both local control and long-term survival appear to be improved with the aggressive combinations including IORT when compared with results achieved with conventional treatments. These findings are consistent from various institutions and countries (MGH, Mayo, Pamplona, Japan; see Chapters 14–16). When residual disease exists after resection of gastric cancers, IOERT with or without external radiation has achieved encouraging survival results (Chapter 11). Excellent local control and long-term survival have been achieved with abdominal and pelvic soft tissue sarcomas with IORT-containing treatment approaches for both primary and recurrent lesions (Chapters 18 and 19). In the randomized National Cancer Institute trial, improved local control was achieved with lower small-bowel morbidity with IOERT plus EBRT versus EBRT alone in patients with marginally resected primary retroperitoneal sarcomas. Mayo Clinic investigators have reported excellent results for locally recurrent as well as locally advanced primary abdominal and pelvic sarcomas. Long-term salvage of approximately 30% has also been achieved with IORT-containing treatment approaches for locally recurrent gynecologic and renal malignancies (Chapters 22 and 23, respectively). With locally unresectable pancreatic cancer, an apparent improvement in local control has been noted with IOERT plus EBRT, but survival has not been altered because of a high incidence of abdominal failure, both liver and peritoneal (Chapter 12). In the treatment of pediatric malignancies with IOERT or HDR–IORT, single-institution reports reveal excellent local control and survival (Chapter 26). In lung cancer management, IOERT has reported promising local control rates when integrated in the multidisciplinary treatment of Pancoast tumors (boosting a tumor bed chest wall region after preoperative chemoradiation plus resection), or in parenchymal lesions with or without mediastinal involvement (Chapter 24). Extremity soft tissue sarcomas are technically simple to treat with IORT (either IOERT or HDRIORT) with attractive results in terms of cosmesis, function, and limb preservation rates (Chapter 20). IORT in the context of multimodal treatment for bladder cancer has proven to be able to sterilize transitional cell carcinoma and should be evaluated more extensively as an addition to chemo-EBRT for bladder preservation (Chapter 23). IORT is also being evaluated in other sites, including bone sarcomas, marginally resected or locally recurrent head and neck cancers, and selected CNS and breast cancers (Chapters 21, 25, 27, and 28, respectively).

HDR-IORT: Physics and Techniques

Intraoperative irradiation using a high dose-rate remote afterloader [1–3] (HDR-IORT) employs the technical and dosimetric advantages of brachytherapy to deliver a large single fraction of irradiation of the target area, while avoiding the surrounding normal tissues.

IORT with Electron-Beam, High-Dose-Rate Brachytherapy or Low-KV/Electronic Brachytherapy: Methodological Comparisons

Intraoperative irradiation (IORT) refers to delivery of a single dose of irradiation to a surgically exposed tumor or tumor bed while the normal tissues are protected from the irradiation either by retracting the mobilized tissue or by shielding the anatomically fixed tissues. IORT has traditionally been performed by using an electron beam as the source of irradiation.