Comparative Effectiveness Research for Prostate Cancer Radiation Therapy

Current Status and Future Directions

Xinglei Shen; Nicholas G Zaorsky; Mark V Mishra; Kathleen A Foley; Terry Hyslop; Sarah Hegarty; Laura T Pizzi; Adam P Dicker; Timothy N Showalter

Disclosures

Future Oncol. 2012;8(1):37-54. 

In This Article

Future Perspective on CER in Prostate Cancer RT

In addition to the high-priority question of treatment options for localized PC,[1] other important CER questions for RT include:

  • Which patients can safely avoid RT or other aggressive treatments altogether, in favor of AS?

  • What are the outcomes after stereotactic body RT, compared with other treatment options, for localized PC?

  • What complementary tools, such as endorectal balloons and image-guidance strategies, are most effective and cost effective for use in PC RT?

  • What are the optimal tools and schedules for patient follow-up after PC RT?

  • Which patients are more or less likely to experience normal tissue toxicities after PC RT, and how can the risk be reduced?

  • For which patients can a strategy of observation with early use of salvage SRT be safely used instead of adjuvant RT in patients with high-risk pathologic features after RP?

The final question, regarding adjuvant RT versus observation with selective use of salvage RT, is particularly urgent. Randomized trials of adjuvant versus observation in patients with extracapsular extension, seminal vesicle invasion or positive margin after RP have consistently reported improved biochemical progression-free survival with adjuvant RT[102,103] and improved survival with longer follow-up.[5] Despite these data, only a small percentage of patients eligible for adjuvant RT receive RT.[137] The rationale for avoiding RT in these patients has been that a strategy of early SRT may offer equivalent survival while sparing RT for a percentage of patients.[138] This strategy is currently being tested in a RCT (the MRC/NCIC RADICALS trial). However, a crucial concern in these patients is their ability to adhere to appropriate follow-up under-usual care conditions. Given the increased scrutiny and close follow-up in randomized studies, this may be inadequately tested in efficacy trials. Instead, the ART-versus-early-SRT question may better be addressed through CER methods. Indeed, regardless of the outcome, comparison of ART versus early SRT will have a profound impact on treatment recommendation for a large subpopulation of patients with PC.

Long-term goals for CER involve development of infrastructure to improve the accuracy and reliability of CER methods. These include expansion of current databases to create more linked data, such as the expansion of SEER-Medicare to younger patients with private insurance, and inclusion of better quality radiation data, such as prescribed dose and dose–volume histogram information for target volumes and normal tissues. Development of improved databases that are linked to a wider range of variable will improve the reliability of observational CER studies. Finally, bringing the concept of effectiveness to the design of prospective trials at a cooperative group level will promote the acceptance and quality of CER results.

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