Comparing the safety of three different radiotherapy regimens: a clinical trial

This study evaluated the safety of two regimens of external beam radiation – short, high-dose radiotherapy – compared with the standard radiotherapy protocol. There were no substantial differences in side effects between the conventional and experimental radiotherapy regimens. 

Prostate cancer which is confined to the gland (localized) can be managed by surgical removal, and different types of radiation therapy. External-beam radiotherapy might be most appropriate for men with localized prostate cancer of intermediate to high risk (characterized by higher Gleason score and PSA levels), and is associated with long-term disease control in most patients. However, it may entail long-term side effects such as urinary dysfunction (due to bladder toxicity). For this reason, attempts to improve radiotherapy regimens, and to decrease the exposure are continuously being done.

In this study, 457 men with localized prostate cancer were randomly assigned in a 1:1:1 ratio to receive conventional radiotherapy or two other regimens of shorter, high-dose radiotherapy:

1. 37 treatments of 2 Gy (intensity) over 7.4 weeks (total of 74Gy) – conventional (standard) radiotherapy (lower-energy radiation, divided into more doses)

2. 20 treatments of 3 Gy over 4 weeks (total of 60 Gy)  – shorter, high-dose (hypofractionated) radiotherapy

3. 19 treatments of 3 Gy over 3.8 weeks (total of 57 Gy) – shorter, high-dose (hypofractionated) radiotherapy.

The treatment was in all cases preceded by complementary hormonal therapy. The trial groups were of similar size and with similar disease progression.

Notably, the high-dose radiotherapy required significantly fewer treatment visits and the overall radiation exposure was lower. The study compared known radiotherapy related side effects, like bowel and bladder toxicity and sexual dysfunction over a period of 2 years. It shows that acute side effects occured earlier in patients treated with high dose radiotherapy but were not worse or more frequent than in patients with the conventional radiotherapy treatment.

This preliminary safety study shows that there are no clinically meaningful differences in side effects between the standard and the significantly shorter hypofractionated radiotherapy schedules.