Predictive models of toxicity with external radiotherapy for prostate cancer

Abstract

The objective of the current study was to analyze the state of the art and present limitations of available predictive clinical models (when available) estimating the risk of genitourinary tract and small bowel complications, erectile dysfunction, and acute and late symptoms of the rectal syndrome caused by prostate cancer external irradiation. An analysis of the literature indicated that very limited attention has been devoted to the development of “integrated,” patient‐tailored, user‐friendly, and clinically usable tools for the prediction of external beam radiotoxicity. In this article, the authors reported on the multivariate correlation between late genitourinary and gastrointestinal toxicities and clinical/dosimetric risk factors, as well as on the first set of nomograms developed to predict acute and late rectal side effects. At the present state of knowledge, the use of nomograms as predictive instruments of radiotoxicity appears to be particularly attractive for several main reasons. They are “user friendly” and easily developed using the results of multivariate analyses, as they weigh the combined effects of multiple independent factors found to be correlated with the selected clinical endpoint. The integrated evaluation of clinical and dosimetric parameters in the single patient can help to provide a tailored probability of the specific outcome considered. Predicting a high probability of toxicity could avoid unnecessary daily costs for the individual patient in terms of quality of life modification during and after treatment, helping patients in the decision‐making process of choosing the best individual, quality of life–related treatment, and clinicians in better tailoring the treatment to patient's characteristics. Cancer 2009;115(13 suppl):3141–9. © 2009 American Cancer Society.

Transitioning from conventional radiotherapy to intensity-modulated radiotherapy for localized prostate cancer: changing focus from rectal bleeding to detailed quality of life analysis

“…[6] have shown that patients are more bothered by symptoms such as soiling, fecal loss, and mucus discharge rather than blood loss, urges, and bowel cramps. Reported risk factors for late incontinence are: a previous abdominal or pelvic surgical procedure [37, 38, 40, 69], diabetes mellitus [40], a history of cardiac problems [40], the use of antihypertensive drugs (a protective factor) [40, 69], prior or acute symptoms (mucous discharge, proctitis) [44, 72, hemorrhoids [66], seminal vesicle irradiation [72], and previous bowel disease [69]. …”

Genetics and genomics of radiotherapy toxicity: towards prediction

“…Theoretical studies have shown that such a test should improve the therapeutic ratio of radiotherapy by allowing dose escalation in radioresistant patients [45]. Predictive clinical models are being developed [71,72]. These cancer type-specific or endpoint-specific models integrate clinical (for example, diabetes, age, smoking, hormonal therapy) and dosimetric (mean doses to critical normal tissues) to obtain an estimate of the probability of developing toxicity.…”

Genomic predictors of prostate cancer therapy outcomes

“…Although radiation dose escalation improves local cancer control [128], it can also increase local toxicity [129]. Late urinary, rectal and sexual morbidity can be debilitating [130], and many models of expected toxicity after EBRT based on clinical and dose intensity have been published [120,131]. However, late toxicity is highly variable, even among patients with identical clinical factors and radiation dose [132] and, thus, other factors may be contributory.…”