Pelvic bone anatomy vs implanted gold seed marker registration for image-guided intensity modulated radiotherapy for prostate carcinoma : comparative analysis of inter-fraction motion and toxicities

الملخص EN

Objectives: We compared the prostate motion variability and toxicities between patients treated with gold marker registration based IG-IMRT (IG-IMRT-M) and bony landmark registration based IG-IMRT (IG-IMRT-B).

Methods: T1c-T3b (node negative), intermediate and high risk (non-metastatic) adenocarcinoma of prostate, age 18 years, Karnofsky Performance Status of 70 were included in this retrospective study.

The prostate motion variability, acute and late radiation toxicities between the two treatment arms (IG-IMRTM versus IG-IMRT-B) were compared.

Results: Total of 35 patients (17 for IG-IMRT-M and 18 for IG-IMRT-B) were treated with a median radiotherapy dose of 76 Gray.

The prostate variability observed with and without markers in millimeter was 4.1 ± 2.3 vs 3.7 ± 2.1 [Antero-Posterior (A-P); p = 0.001], 2.3 ± 1.5 vs 2.1 ± 1.2 [Superior-Inferior (S-I); p = 0.095] and 1.1 ± 1.7 vs 0.4 ± 1.4 [Left-Right (L-R); p = 0.003].

There was higher acute toxicity in IG-IMRT-B arm compared to IG-IMRT-M arm in terms of grade 2 diarrhea [50% vs 11% OR = 7.5 (1.3–42.7); p = 0.02] and grade 2 proctitis [38% vs 5.8%, OR = 10.1 (1.09–94.1); p = 0.04].

At a median follow up of 36 months, the late genitourinary toxicities grade 2 [27% vs 0%; p = 0.04] were higher in the IG-IMRT-B arm compared to IG-IMRT-M arm.

Conclusions: IG-IMRT-M detects higher prostate motion variability as compared to IG-IMRT-B, inferring a significant prostate motion inside fixed pelvic bony cavity.

The addition of marker based image guidance results in higher precision of prostate localization and lesser acute and late toxicities