# Cost-effectiveness analysis of intensity modulated radiation therapy versus robot-assisted radical prostatectomy for patients with low-risk prostate cancer in Japan

## TL;DR

This study compares the cost-effectiveness of radiation therapy and surgery for low-risk prostate cancer in Japan, finding radiation therapy to be a more efficient option.

## Contribution

The study introduces a Japan-specific cost-effectiveness analysis of hypofractionated radiation therapy versus prostatectomy for low-risk prostate cancer.

## Key findings

- IMRT-20 showed a modest QALY gain over RARP with an ICER of JPY 143,685 per QALY.
- IMRT-20 was cost-effective in 78.1% of simulations under probabilistic sensitivity analysis.
- Excluding sexual dysfunction disutility made RARP more favorable, but IMRT-20 became better when disutility exceeded 20%.

## Abstract

This study evaluated the cost-effectiveness of hypofractionated intensity-modulated radiation therapy delivered in 20 fractions (IMRT-20) compared with robot-assisted radical prostatectomy (RARP) for patients with localized low-risk prostate cancer in Japan. A state-transition Markov model was developed from the Japanese healthcare system, using Japanese-specific cost data. Clinical probabilities, adverse event rates and health utility values were primarily derived from international sources, including the ProtecT trial, with extensive sensitivity and scenario analyses to address parameter uncertainty. The base-case analysis compared IMRT-20 and RARP. Scenario analyses included conventional fractionated IMRT (IMRT-38) versus RARP, as well as IMRT-20 versus RARP excluding the utility decrement associated with sexual dysfunction to explore preference-sensitive outcomes. Model outputs included quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs) and incremental net monetary benefit (INMB). In the base-case analysis, IMRT-20 yielded a modest QALY gain (0.1164) at slightly higher costs compared with RARP, resulting in an ICER of JPY 143 685 per QALY, well below the Japanese willingness-to-pay threshold of JPY 5 000 000 per QALY. Probabilistic sensitivity analysis showed that IMRT-20 was cost effective in 78.1% of simulations. IMRT-38 was less cost effective because of longer treatment duration and higher resource utilization (ICER JPY 3 317 380 per QALY), although it remained below the threshold. When the disutility of sexual dysfunction was excluded, IMRT-20 was dominated by RARP; however, INMB analysis indicated that IMRT-20 became economically favorable when the disutility exceeded 20%. Overall, IMRT-20 represents a clinically and economically efficient definitive treatment strategy for localized low-risk prostate cancer in Japan, supporting value-based cancer care.