Impact of mean rectal dose on late rectal bleeding after conformal radiotherapy for prostate cancer: Dose–volume effect

The Impact of Varying Volumes in Rectal Balloons on Rectal Dose Sparing in Conformal Radiation Therapy of Prostate Cancer

“…The dose constraints of Boersma et al [1], Cozzarini et al [3], Greco et al [16], Fiorino et al [9,11], Koper et al [20], and Zapatero et al [28] can easily be met in our study without using a rectal balloon in case of irradiation of the prostate only (Tables 1 and 2). We can conclude from our data that the risk for chronic rectal toxicity ≥ grade 2 in all patients in our study who were treated with irradiation of the prostate only was < 5% -with or without the use of a rectal balloon.…”

“…Several investigations indicate a relationship between DVHs and the development of chronic rectal toxicity [1,3,9,11,16,20,28]. To associate the rectal DVHs in our study with an estimated risk for chronic rectal toxicity, the results were compared with studies analyzing relationships between dose volume and rectal toxicity.…”

“…In a recently published study Fiorino et al recommended to keep the volume of the rectum exposed to 50 Gy < 60-65%, the volume of the rectum exposed to 60 Gy < 45-55%, and the volume of the rectum exposed to 70 Gy < 25-30% to keep the rate of moderate/severe rectal bleeding < 5-10% [11]. Zapatero et al found no rectal bleeding when the rectal volume exposed to 60 Gy was < 42% compared to 7.7% rectal bleeding when > 60 Gy were exposed to > 42% of the rectal volume [28].…”

“…Rectal toxicity following external beam irradiation of prostate cancer correlates with radiation dose, exposed rectal wall volume, in particular with the percentage of rectal volume included in the intermediate and high dose volume [1,16,20,27,28]. Efforts in optimizing external beam radiation to the prostate are aiming to increase the total dose applied to the prostate while minimizing the delivered dose to the organs at risk, e.g., the rectum [5,6,13,25].…”

Predictive models of toxicity in external radiotherapy

“…[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The reliability of DVH constraints in predicting the risk of late rectal toxicity is highly influenced by the management of rectal filling: A ''full'' rectum at the planning scan is less likely to represent the dose actually delivered to the rectum, 23 and the practice of emptying the rectum also reduces the differences in calculating the DVH of the whole rectum (including filling) and of the wall. 24 Conversely, it is also very important to remember that most studies that have assessed DVH constraints for late rectal bleeding have used a very similar ''anatomic-based'' definition of the cranial-caudal extension of the rectum.…”