The aim of the study is a medico-economic evaluation to estimate a cost differential between three modalities of Intensity-Modulated Radiation Therapy for cancers of the prostate, cervix and anal canal with pelvic lymph node irradiation : treatment with helical Tomotherapy and dynamic arc therapy using two different technologies: RapidArc or VMAT.

- Treatment by IMRT: Radiotherapy Modalities. All volumes will receive a base dose of 45 Gy in 25 fractions or 46 Gy in 23 fractions, followed by additional irradiation doses that vary depending on the type of tumor. The treatment will be carried out in one or more phases.

• Patient follow-up:

this will take place at 3 months, 6 months, 12 months, and 18 months after the end of irradiation for cervical and anal canal cancers, and extended to 24, 30, and 36 months, then at 4 and 5 years for prostate cancers, with an evaluation of the treatment's effectiveness and tolerance.

• Collection of economic and clinical information: Medical data concerning the patient, their disease, and treatment-related toxicity will be collected during the treatment and afterward. The economic study will include measuring the duration of the different stages of preparation and treatment.

Inclusion Criteria:

• WHO performance index ≤ 2
• Age > 18 years
• Histologically confirmed carcinoma
• Locally advanced anal canal cancer (> 4 cm and/or N1 to N3), requiring irradiation of inguinal and pelvic lymph nodes with concomitant chemotherapy
• Prostate cancer requiring pelvic lymph node irradiation and hormone therapy
• Cervical cancer requiring irradiation of the pelvic lymph nodes, the primary tumor, and parametria with concomitant chemotherapy. Surgical resection may be performed after chemoradiotherapy depending on each center's practices. Boosts via external beam radiotherapy or brachytherapy are accepted
• The investigator must ensure that the patient has not expressed its opposition to participate in this study. The signing of a consent form is optional;

Exclusion Criteria:

• History of invasive cancer (except basal cell carcinoma)
• Indication for re-irradiation
• Lombo-aortic lymph node irradiation
• Postoperative radiotherapy
• Geographic distance likely to interfere with patient follow-up