Late radiation effects to the rectum and anus after treatment for prostate cancer; validity of the LENT/SOMA score.

BACKGROUND

The Late Effects Normal Tissue/Subjective Objective Management Analytic (LENT/SOMA) system for grading of side effects after radiotherapy was proposed several years ago. Only a few studies have previously been performed on the validity of the LENT/SOMA. The aim of the present study was to validate the LENT/SOMA scoring system for recto-anal side effects after treatment for prostate cancer in a randomized trial.

MATERIAL AND METHODS

A total of 875 patients with locally advanced prostate cancer were randomized to either hormonal treatment alone or hormonal treatment plus radiotherapy in the Scandinavian Prostate Cancer Group 7 (SPCG-7) study. At least three years after treatment was started, the 178 patients that were randomized at St. Olavs Hospital were approached. One hundred and three patients of these accepted inclusion. The side effects according to LENT/SOMA were graded by oncologist and nurse. In addition, side effects were graded according to the European Organisation for Research and Treatment of Cancer and the Radiation Therapy Oncology Group (EORTC/RTOG) toxicity scale and patient-reported health-related quality of life (HRQOL) questionnaires. Content/face validity, sensitivity and inter-rater reliability of the LENT/SOMA tables for rectum were analyzed.

RESULTS

Content/face analysis of LENT/SOMA revealed serious problems. Significant correlations (Spearman's rho > 0.4) were found between three of 15 LENT/SOMA items and similar HRQOL items. LENT/SOMA score made it possible to detect significant differences between the two groups of patients (p < 0.001), EORTC/RTOG toxicity score did not (p = 0.138). Inter-rater reliability was acceptable.

CONCLUSIONS

LENT/SOMA scoring system for recto-anal side effects after radiotherapy for prostate cancer displays serious difficulties in the present study. Replacement of LENT/SOMA tables for rectum by a combination of patient-reported HRQOL questionnaires, clinical examination and objective physiological measurements might be called for.