The Scalpel and the Beam: Radiotherapy for the Surgeon

Treating cancer is very often best done through a multimodal approach and the (oncologic) surgeon must strive to become a (surgical) oncologist. As radiotherapy becomes more widely available, it is increasingly important for all surgeons to be aware of its principles, indications and limitations to understand how to integrate radiotherapy in the range of therapeutic options. To provide the best treatments available, the surgical, medical and radiation oncologists must work in close cooperation, each having a deep understanding of the others’ specialties in order to determine what their role will be in the optimal treatment plan. The precise indications for a combination of surgery and radiotherapy in veterinary oncology are too many to be listed here, and more information on the application to particular tumour types in available elsewhere.

What surgeons need to know about radiotherapy
In its most common indications, radiotherapy is similar to surgery in that it is a local treatment used to treat solid tumours. It uses ionising radiation to cause cell death through damage to critical molecules such as DNA. This damage to critical cellular molecules is either caused by direct effect or through the formation of free radicals near them. Oxygen is therefore important in the cellular response to radiation and well oxygenated cells are more radiosensitive than hypoxic ones. As DNA is a major target of radiation-induced cellular damage, much of the resulting cell death occurs at the time of the next cell division (reproductive death). Consequently, the effects of radiotherapy are not readily apparent but are variably delayed depending on the cellular turnover rate of the irradiated tissues. Tissues with a rapid cellular turnover are therefore called “acutely-responding” and those with a slower turnover “late-responding”. Although radiotherapy takes advantage of the differences in cellular biology (repair capacities, cellular turnover, etc.) between normal and neoplastic tissues to preferentially be detrimental to tumour cells, it is non-selective and normal tissues in the radiation field will also be affected. As it is not yet possible to strictly limit the administration of radiotherapy to neoplastic tissues, the tolerance to radiation of the normal tissues included in the radiation field is the limiting factor of the maximal dose of radiation which can be administered for treatment of a tumour.  [...]