Timescale of Evolution of Late Radiation Injury after Postoperative Radiotherapy of Breast Cancer Patients
Presenter: Silvia Johansson
Affiliation: Umea University Hospital, Sweden
Most of the modern randomized trials in breast cancer document toxicity associated with treatment, but none document these toxicities over the scale of decades. These data are important because many women are diagnosed with breast cancer at a relatively young age, and because these women, once cured, have a potential life span of many decades.
This study reviewed the histories and treatments of 71 patients treated with mastectomy, axillary lymph node dissection, and post-operative radiation therapy (RT) to the parasternal, axillary, and supraclavicular lymph nodes using Cobalt teletherapy, 44 Gy in 11 fractions. Seventy-seven percent of patients received androgen ablation in the form of either oophrectomy or radiative ablation of the ovaries. No patient received chemotherapy.
- Median survival of all patients was 12 years, although patients below the median age had a median survival of 28 years.
- Five of 71 patients had a locoregional recurrence within the irradiated field, with 8 additional chest wall recurrences.
- The re-calculated dose to the brachial plexus due to field overlap was 57 Gy, given in 16-17 fractions over 3-4 weeks.
- The incidence of lymphedema at 5 and 30 years were 80% and 86%, respectively, while arm paralysis at 5 and 30 years was 20% and 49%, respectively.
- At 30 years of follow up, incidence of fibrosis, bone necrosis, and vocal cord paresis were 86%, 33%, and 5%, respectively.
- Median time to presentation of toxicity for lymphedema, bone necrosis, arm paralysis, and vocal cord paresis were 2 years, 5 years, 7 years, and 20.5 years, respectively.
- These data were obtained in patients in whom sub-optimal treatment techniques and large fraction sizes were employed. It is well known that large fraction size translates directly into increased chance of long term toxicity.
- In the present day, many patients in this population would be likely to receive chemotherapy, smaller radiation fraction sizes, and higher energy X-rays to the irradiated areas. Hence, a direct comparison between the patients in this study and those receiving contemporary post-mastectomy lymph node radiation is not appropriate.
- This study underscores the necessity of accurate treatment planning with minimization of hot spots at the field junctions. It also reminds us that the after effects of radiation therapy may not cease after "long term" follow up of 5 or 10 years.
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