Urological cancer experts were warned on the far-reaching consequences of high-dosage radiation therapy with a dedicated session that examined the complications and clinical management of radiation-related pelvic cancers held today at the 8th European Meeting on Urological Cancers (EMUC16) in Milan, Italy.
With the session chaired by George Thalmann (CH) and Peter Hoskin (GB), the issues covered were the risk of secondary cancers, pathophysiology and therapy and the immune effects due to pelvic radiotherapy.
Radiation oncologist Michael Pinkawa (DE) discussed the risks and features and cautioned that absorbed dosage is directly related to the severity of complications.
“The probability of the effect depends on the absorbed dose,” said Pinkawa. “The severity is independent of the absorbed dose.” He noted that studies showed that effect does not occur below a threshold dose.
Prevention, according to Pinkawa, does not only have a crucial role but should be a chief concern among doctors.
“As late effects are often difficult to treat, prevention of radiation toxicity has the highest priority,” he said as he mentioned that dose-volume-effects for organs are well-known. Pinkawa: “Careful patient preparation and application of modern treatment techniques allow high doses to tumour without relevant risk for severe late toxicities.”
He said surgical intervention in a previously irradiated area is linked to a higher rate of complications such as urethral stricture and incontinence. “Surgical intervention, even biopsies, early after irradiation can cause persistent inflammation, decrease healing and precipitate fistula formation,” Pinkawa said.
In his take-home messages, Pinkawa stressed that parenchymal cells, vasculature and connective tissues are all important pathogenetic components. “All late radiation effects are never completely repaired and can be thus difficult to treat,” he added.
Cesare Cozzarini (IT), meanwhile, discussed some aspects of radiation-induced secondary primary cancers (SPCs) after pelvic RT, which he described as a “potentially growing problem.”
“A thorough assessment of the risks of SPCs after (and therefore potentially as the result of) pelvic RT requires the comparison between irradiated and not irradiated patients, and the knowledge of the intrinsic risk of SPCs in patients affected by different primary pelvic tumours
Cozzarini also said that pelvic RT seems to definitely increase the risk of leukemia but not of other hematologic malignancies.
Meanwhile, medical oncologist Michele Mondini (FR) discussed the immune effects of pelvic radiotherapy and said studies have shown that radiotherapy increases tumour-associated macrophages in a prostate cancer model. He said that ionizing radiation is “more than a killer but actually acts like a secret agent,” which causes immunogenic cell death. He made the “secret agent”” analogy in describing the impact of radiation as essentially providing “guidance to the target” and re-polarising macrophages.