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External beam radiotherapy (EBRT) is a well-established curative treatment for localized prostate cancer. Acute and late toxicity rates after EBRT can be considerable and have been the subject of many studies. Dose-volume effect relationships have been described extensively. In the early years of radiotherapy, the "skin erythema dose" was used for the definition of tolerable doses. During subsequent years, it was realized that no relationship between acute reactions to radiation exposure and late sequelae in other organs and tissues could be established in the majority of patients. More aggressive radiotherapy protocols can result in aggravation, i.e. an increase in severity and duration, of acute radiation effects. Particularly in those organ systems in which a barrier against mechanical and/or chemical stress is established by the acutely responding component - a non-healing acute response can directly progress into a late effect. This phenomenon has been termed a consequential late effect.

The aim of this study was to answer the question if, and to which extent, acute symptoms at the end and/or several weeks after EBRT can predict adverse urinary and gastrointestinal long-term quality of life (QoL). Patients (n=298) responded to a QoL questionnaire (EPIC=Expanded Prostate Cancer Index Composite) before, at the last day, two months (median time) after, and more than one year after treatment. QoL score changes in the urinary and bowel domain relative to the baseline scores before treatments indicated the extent of QoL impairment.

In contrast to absolute scores after EBRT, quality of life changes could not be predicted by pretreatment scores. Consequential late effects play a major role after radiotherapy for prostate cancer. Long-term gastrointestinal symptoms were well predicted by symptoms at the end of, and several weeks after treatment, suggesting an inefficiency of the repair system and a non-healing acute response. Urinary symptoms without recovery within a few weeks after radiotherapy are likewise highly predictive for adverse long-term urinary quality of life. Patients reporting great/moderate bother with urinary/bowel problems two months after EBRT reported to have great/moderate bother > one year after EBRT in > 50%, respectively. Only < 7% of patients without great/moderate bother with urinary/bowel problems at time C reported to have great/moderate bother at time D.

Patients with greater and longer acute toxicity are candidates for closer follow-up and possible prophylactic actions to reduce a high probability of long-term problems, including possibly a total dose reduction for selected patients with particularly bothersome acute gastrointestinal problems.

Source: UroToday