Prostate-only Versus Whole-Pelvis Radiation with or without BT Boost for GGG 5

Prostate-only Versus Whole-pelvis Radiation with or Without a Brachytherapy Boost for Gleason Grade Group 5 Prostate Cancer: A Retrospective Analysis [2020, Full Text]

From the Abstract:
"Patient summary
When men with a high Gleason grade prostate cancer receive radiation with external radiation and brachytherapy, the addition of radiation to the pelvis results in a longer duration of prostate-specific antigen control. However, we did not find a difference in their survival from prostate cancer or in their survival without metastatic disease. We also did not find a benefit for radiation to the pelvis in men who received radiation without brachytherapy."

From the Discussion:
"Contrary to an increased push toward extended lymphadenectomy within the urologic community [18], [19], enthusiasm for WPRT has dwindled over the years among radiation oncologists [20]. In this series of patients with aggressive GG 5 disease, only 53% received WPRT, despite the known high incidence of pathologic node positivity in patients with GG 5 disease who undergo surgery (17% in a companion cohort) [10]."

"Conclusions
The role of WPRT remains a contentious topic in PCa radiation oncology. In this study, we analyzed the benefit of WPRT in patients with GG 5 disease, a group at a much higher a priori risk of having occult nodal metastases, based on prostatectomy series and emerging data with advanced imaging agents. Overall, WPRT was not associated with a benefit in bRFS. However, on subgroup-specific analysis, WPRT was associated with a significant benefit in patients receiving EBRT + BT, but not EBRT alone. These data suggest that in the highest-risk patients, if local control is achieved in the prostate, WPRT may be valuable in sterilizing regional microscopic disease. The lack of an association with clinical outcome benefits could be attributed to lack of power and may become apparent with time. Further studies designed to optimize WPRT, including with the use of more potent radiosensitizing ADT agents and/or optimization with advanced imaging, are warranted."

("lack of power" refers to statistical power, basically the number of cases examined relative to the number needed to test a hypothesis)

The interesting Discussion section brings up a number of yet-unresolved questions as to who may see benefit and why.

ASCO Post editorial about this study

This study brings up an issue that I usually mention when discussing, for example, the 15-year results of newer RT modalities like SBRT: improved BCR numbers may or may not translate into an improvement in clinical recurrence or PCa-specific survival.

Djin

Post Edited (DjinTonic) : 1/11/2020 9:05:11 AM (GMT-7)

Corrected -- thanks, Mumbo!
Djin

JNF said...
Based on the numbers of my dx and a few enlarged nodes on the CT scan everything was radiated. Uro, RO, an MO all concurred without a discussion.

That makes perfect sense when you suspect lymph-node invasion. I didn't have primary RT, so I don't know how I would feel about pelvis-only if LNI is not suspected.

Djin

My wife had all the nodes removed from her underarm due to breast cancer and continues to suffer from severe chronic lymphadema in her arm requiring frequent physical therapy and wears a compression sleeve 24/7/365. It will never get better due to the surgical removal.

Radiating the nodes is very different for side effects as the radiation therapy does not disrupt the lymphatic system the same as removing them does. The side effects are more from the radiation of the intestines and bladder that are in the path. Thankfully, I have had no negative treatment side effects and the side effects during the radiation were in line with expectations and disappeared when the radiation stopped.

Radiating the pelvic lymph nodes in high risk situations is common and uncommon in lower risk situations. This analysis is simply helping to refine the use of the radiation to provide better treatment direction to the docs.