The number of radiation treatments a patient receives after a prostatectomy varies significantly based on the clinical situation and the specific radiation schedule chosen. Post-operative radiation therapy, often called post-prostatectomy radiation, is a common follow-up treatment used to target any remaining microscopic cancer cells in the area where the prostate gland was removed. The final count of treatment sessions, or fractions, is influenced by the treatment goal, the total radiation dose required, and whether a conventional or accelerated schedule is used. This number can range from as many as 45 daily sessions over several weeks to as few as five sessions.
Indications for Post-Prostatectomy Radiation Therapy
Post-prostatectomy radiation is categorized into two main approaches based on timing and reason: adjuvant or salvage. The decision to recommend radiation relies on specific pathological and biochemical findings following surgery. These findings indicate a higher risk that cancer cells may have been left behind.
Adjuvant radiation therapy is given shortly after surgery, often within a few months, while the patient’s prostate-specific antigen (PSA) level is still undetectable. This prophylactic approach prevents recurrence in patients with high-risk features identified in the removed tissue. These features include positive surgical margins or evidence that the cancer extended beyond the prostate capsule, such as seminal vesicle invasion.
Salvage radiation therapy is administered later, specifically in response to a detectable and rising PSA level, which signals biochemical recurrence. This rising PSA indicates the cancer has returned, either locally in the prostate bed or elsewhere. Early salvage radiation, when the PSA is very low (below 0.5 ng/mL), is considered the most effective time to intervene to eradicate recurrent cancer cells while the disease burden is small.
Conventional Radiation Schedule (The Standard Answer)
The traditional approach uses a conventional fractionation schedule, delivering a small dose of radiation each day over an extended period. This method was historically preferred because it allows healthy, surrounding tissues, such as the rectum and bladder, time to repair between treatments. In this conventional setting, the number of treatments is typically between 33 and 37 fractions.
This regimen usually translates to a total duration of approximately six and a half to seven and a half weeks, with treatments administered five days a week. The total radiation dose delivered to the surgical bed generally falls in the range of 66 to 70 Gray (Gy). Each daily fraction is a small, consistent amount, often 1.8 to 2.0 Gy per session, accumulating the total prescribed dose.
Hypofractionation: Fewer Treatments, Higher Doses
Hypofractionation is a modern approach that significantly reduces the total number of treatment sessions by delivering a higher dose of radiation per session. This method utilizes the biological properties of prostate cancer cells, which are sensitive to larger radiation doses. Hypofractionation offers a shorter treatment course, which is more convenient for patients and may reduce healthcare costs.
In a moderately hypofractionated schedule, the total number of fractions is typically reduced to 20 to 28 treatments. This condenses the treatment time to about four to six weeks, compared to the seven or more weeks required for conventional fractionation. For instance, a common regimen delivers a total dose of 62.5 Gy in 25 fractions of 2.5 Gy each. Clinical trials show this approach is comparable to the conventional schedule regarding cancer control and late side effects.
A more intensified form, stereotactic body radiation therapy (SBRT), can reduce treatment to as few as five sessions. SBRT delivers an extremely high dose of radiation in a highly focused manner. This ultra-short schedule is still being investigated in the post-prostatectomy setting to ensure its long-term safety profile is equivalent to longer schedules. The choice between conventional and hypofractionated treatment depends on individual patient factors and the treating physician’s recommendation.
The Patient Experience: Steps in Radiation Delivery
The process of receiving post-prostatectomy radiation therapy begins with a thorough consultation and imaging. The radiation oncologist uses recent CT or MRI scans to precisely map the area requiring treatment. This mapping is followed by a simulation session, where the patient is positioned on the treatment table and marks are placed on the skin to ensure accurate daily setup.
The next step is treatment planning, where a medical physicist and the radiation oncologist use computer software to design the radiation beam arrangement. This plan ensures the maximum dose is delivered to the prostate bed while minimizing exposure to nearby organs like the bladder and rectum. Once approved, the patient begins the daily treatment sessions, typically scheduled Monday through Friday.
Each daily radiation session is brief, often lasting only 10 to 20 minutes from entry to exit. The actual delivery of the radiation beam takes only a few minutes. The majority of the time is spent on image-guided radiation therapy (IGRT) to confirm the patient’s exact position. Following the completion of the full course, the patient enters a long-term follow-up phase, including regular check-ups and PSA blood tests to monitor for recurrence.