What are the conventional fractionation radiotherapy doses for the prostate, pelvic lymph nodes, and para‑aortic lymph nodes in a typical adult male with localized or high‑risk prostate cancer?

Conventional Fractionation Radiotherapy Doses for Prostate Cancer

For conventional fractionation radiotherapy in prostate cancer, deliver 74-79 Gy to the prostate, 44-50 Gy to the pelvic lymph nodes in high-risk disease, and 44-50 Gy to para-aortic nodes when indicated, all using modern IMRT techniques with daily image guidance. 1, 2

Prostate Dose

• The prostate should receive at least 74 Gy and can be escalated to 79 Gy using conventional fractionation (1.8-2.0 Gy per fraction). 1
• Dose escalation to 74-78 Gy significantly improves biochemical control rates and delays salvage hormonal therapy compared to lower doses of 64-70 Gy, based on multiple randomized controlled trials. 1
• Modern techniques including IMRT and image-guided radiotherapy (IGRT) are mandatory when delivering doses ≥78 Gy to limit side effects while maintaining tumor control. 1, 2
• The NCCN specifically recommends 78-80+ Gy for high-risk disease to improve PSA-assessed disease control. 2

Pelvic Lymph Node Dose

• Elective pelvic lymph nodes receive 44-50 Gy when treating high-risk prostate cancer. 2
• This elective dose targets areas at risk for microscopic nodal involvement, including obturator, internal and external iliac, presacral, and sacral lymph node regions. 2
• Pelvic nodal irradiation is a Category 1 recommendation for high-risk patients (T3-T4, Gleason 8-10, or PSA >20 ng/mL) and should be combined with 24-36 months of androgen deprivation therapy. 2
• For intermediate-risk patients, pelvic nodal irradiation may be considered but is not mandatory, using the same 44-50 Gy dose range. 2
• Low-risk patients should NOT receive pelvic lymph node irradiation as it adds toxicity without oncologic benefit. 2

Para-aortic Lymph Node Dose

• Para-aortic lymph nodes, when treated, receive the same elective dose of 44-50 Gy as pelvic nodes. 2
• Para-aortic nodal irradiation is reserved for very high-risk cases with significant risk of para-aortic involvement, though this is not routine practice for most high-risk prostate cancer. 2
• The treatment volume and dose follow the same principles as pelvic nodal irradiation, targeting microscopic disease. 2

Critical Technical Requirements

• Daily IGRT is essential when delivering doses >75 Gy to the prostate to ensure accuracy and minimize toxicity to adjacent organs. 2
• IGRT techniques include CT, ultrasound, implanted fiducials, or electromagnetic tracking. 2
• IMRT or VMAT should be the minimum technical standard for dose delivery, avoiding non-modulated 3D conformal techniques. 1, 2
• Maintain a prostatic-rectal interface margin ≤10 mm when using IGRT to minimize rectal toxicity. 2

Important Caveats

• Do not use the standard 44-50 Gy elective nodal dose for grossly involved lymph nodes—these require higher doses of 54-66 Gy if anatomically feasible. 2
• The simultaneous integrated boost (SIB) technique can be used to deliver different doses to the prostate and nodes concurrently, though sequential approaches (nodes first, then prostate boost) are also acceptable. 3
• For salvage radiotherapy after prostatectomy treating only biochemical recurrence, a minimum dose of 66 Gy to the prostatic fossa is recommended. 1