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Potential Delays in Beginning Radiation Treatments

What potential issues may cause a delay in beginning radiation treatments for breast cancer patients?

The three common treatment modalities in treatment of breast cancer can be given in different sequences. The most common sequence is to start with surgery, continue with chemotherapy if indicated and finish with radiation therapy. But in some cases chemotherapy is delivered before surgery and is followed by radiation therapy. There is one exception to this general rule of radiation therapy being the last modality in the sequence of treatments and that is when Accelerated Partial Breast Irradiation (APBI) using brachytherapy balloons such as Mammosite, Contura or Savi applicator is the form of radiation utilized. In APBI, radiation is delivered immediately after surgery and chemotherapy, if recommended, would follow radiation.

Therefore a “delay” in beginning of radiation treatment can be a planned or an unplanned one. For example we often recommend 4-6 weeks between surgery and beginning of radiation in order to make sure that all the surgical incisions are completely healed. One of the potential side effects of radiation is delay in healing of wounds and that is the reason behind that planned delay. We also recommend about 2-4 weeks of gap between last chemotherapy administered and beginning of radiation therapy. This form of planned delay in beginning of radiation is due to the fact that some chemotherapy agents are radiosensitizers and may potentially increase the risk of side effects from radiation therapy.

The unplanned or undesired delays in beginning of radiation therapy may be due to an unhealed surgical incision or persistent seroma or a hematoma in the lumpectomy cavity or in soft tissue pouches after a mastectomy. Radiation therapy is based on very accurate measurements and calculations of the volumes of tissue irradiated and the doses delivered. If the calculations and radiation plan is based on a certain size of breast and certain size of lumpectomy cavity and this volume is changed due to an enlarging seroma or hematoma, our calculations and therefore radiation doses would be off. Therefore we would await resolution of a seroma or a hemtoma either by giving it some time to absorb or by aspirating it before planning the radiation treatment.

With increase in the use of tumor genetic assay tests such as Oncotype DX, often there is a delay in determining whether a patient requires chemotherapy or not. In this scenario, the radiation oncologist would need to await the test result before starting patient’s radiation because if the Oncotype DX result indicates benefit from chemotherapy, this treatment should be delivered before beginning of radiation therapy.