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Radiation therapy for prostate cancer
Medical expert of the article
Last reviewed: 06.07.2025
It is believed that the long-term results of radiation therapy for prostate cancer are the same as with surgical treatment, and the quality of life is not affected. Since 1990, the possibilities of radiation therapy have been expanded due to the introduction of contact irradiation and volumetric planning. In recent years, specialized centers have increasingly used modulation of the irradiation intensity.
Comparative studies of the effectiveness of radiation therapy (external or contact) and prostatectomy for localized prostate cancer have not yet been obtained.
The surgeon and radiologist are involved in choosing the treatment tactics. The stage of the disease, Yandex Gleason, PSA level, life expectancy, and side effects of treatment should be taken into account. The patient should be given all information about the diagnosis and treatment options. The final decision is made by the patient. As with radical prostatectomy, the Gleason index is considered the most important prognostic factor.
Prostate cancer irradiation technique
Volumetric planning of radiation fields is performed based on CT performed in the position in which the patient will be irradiated. A clinical volume (tumor volume) is allocated, which together with the surrounding healthy tissues makes up the therapeutic volume. Multi-leaf collimators automatically give the radiation field the desired shape. Visualization of radiation fields allows real-time comparison of actual fields with simulated ones and correction of deviations exceeding 5 mm. Volumetric planning helps to increase the dose and, accordingly, the effectiveness of irradiation without increasing the risk of complications. Modulation of irradiation intensity is possible on a linear accelerator equipped with a modern multi-leaf collimator and a special program: the movement of the collimator flaps evenly distributes the dose in the radiation field, creating concave isodose curves. Radiation therapy (regardless of the technique) is planned and carried out by a radiologist, dosimetrist, engineer-physicist and programmer.
Radiation therapy for prostate cancer T 1-2c N 0 M 0
For patients with low oncological risk T 1-2b ( Gleason index less than 6, PSA level less than 10 ng/ml), the dose for external irradiation is 70-72 Gy; increasing it does not improve the results.
In moderate risk (T 2b, PSA level 10-20 ng/ml or Gleason score 7), increasing the dose to 76-81 Gy significantly improves 5-year relapse-free survival without causing severe late radiation reactions. Randomized trials have shown that increasing the radiation dose is justified in the moderate risk group. One study compared the effect of 70 and 78 Gy (with conventional and volumetric planning, respectively) in 305 patients with T 1-3 tumors and a PSA level of more than 10 ng/ml. With a median follow-up time of 40 months, 5-year relapse-free survival was 48 and 75%, respectively. Another trial included 393 patients with T 1b-2b tumors (in 15% of cases, the Gleason score was less than 6, the PSA level was less than 15 ng/ml). In the first group, patients underwent proton beam irradiation of the prostate gland at a dose of 19.8 isogy, followed by irradiation of a larger volume of the gland at a dose of 50.4 Gy. In the second group, the proton beam irradiation dose was increased to 28.8 isogy. With a median follow-up time of 4 years, the 5-year relapse-free survival in the first group was significantly higher than in the second. The optimal dose has not yet been determined, but a dose of 78 Gy can be recommended for everyday practice.
In the high-risk group (T2c , Gleason score greater than 7, or PSA level greater than 20 ng/mL), increasing the radiation dose increases relapse-free survival but does not prevent relapses outside the pelvis. According to a randomized trial that included 206 patients (PSA level 10-40 ng/mL, Gleason score of at least 7, or tumor extension beyond the capsule; median follow-up time 4.5 years), adding hormonal therapy to radiation therapy with volumetric planning for 6 months significantly increases survival, reduces the risk of tumor-related death, and prolongs the time until the start of hormonal therapy.
Adjuvant radiotherapy for prostate cancer T3
Adjuvant radiotherapy is more successful in patients with evidence of extracapsular invasion or positive surgical margins than in patients with seminal vesicle invasion or lymph node metastasis. If the tumor extends beyond the prostate capsule (pT3), the risk of local recurrence reaches 10-50%. As mentioned above, the risk depends on the PSA level, Gleason score, and the presence of tumor cells at the resection margin. Adjuvant radiotherapy is well tolerated: severe urinary tract complications may occur in 3.5% of cases; urinary incontinence and strictures in the anastomotic zone occur no more often than without radiation. The five-year relapse-free survival is 12.2% (in the control group - 51.8%).
If the PSA level is below 0.1 ng/ml 1 month after surgery and capsule or seminal vesicle invasion is detected (pT 3 N 0 ), tumor cells are at the resection margin, adjuvant radiation therapy is indicated. It is started immediately after normalization of urination and wound healing (after 3-4 weeks). Another option is dynamic observation in combination with radiation (with a PSA level of more than 0.5 ng/ml). Since with a PSA content of more than 1 ng/ml, the effectiveness of radiation therapy significantly decreases. The radiation dose to the bed of the removed prostate should be at least 64 Gy. Radiation therapy is usually performed immediately after surgery.
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Radiation therapy for tumors T 3-4 N 0 M 0 and T 1-4 N 1 M 0
Unfortunately, despite the success of early diagnostics, such tumors are observed in Russia more often than in developed countries. Due to the high risk of micrometastasis, the radiation field should include not only enlarged (N 1 ), but also externally unchanged pelvic lymph nodes (N 0 ). Isolated use of radiation therapy in such cases is ineffective, therefore, given the hormone-dependent nature of prostate cancer, it is combined with hormone therapy.
Numerous studies confirm the advantages of combination therapy: a reduction in the risk of distant metastasis (due to the destruction of micrometastases), an increase in the effect on the primary tumor - a potential source of new metastases (by increasing apoptosis against the background of irradiation).
Prophylactic irradiation of pelvic lymph nodes
Metastasis to the pelvic lymph nodes worsens the prognosis, but randomized trials conducted in the 1970s and 80s did not confirm the effectiveness of their prophylactic irradiation. Radiation exposure to the lymph nodes does not affect the risk of local recurrence and survival. Partin nomograms and a special formula allow assessing the risk of metastasis to the lymph nodes;
Risk of metastasis (%) = 2/3 PSA + (Gleason score 6) x 10.
Lymph node biopsy may also be performed during laparoscopy or laparotomy.
Modulation of irradiation intensity
Intensity modulation of radiation allows increasing the dose to 80 Gy with uniform distribution in the tumor and without additional damage to healthy tissues. The Memorial Sloan-Kettering Cancer Center in New York has the most experience in using modulation: in 1996-2001, 772 patients received radiation therapy at a dose of 81-86.4 Gy. With a median observation time of 2 years (6-60 months), the risk of developing moderate radiation proctitis was 4%, cystitis - 15%; three-year relapse-free survival in the low, medium and high risk groups was 92, 86 and 81%, respectively. The method allows increasing the radiation fractions, thereby reducing the treatment time (for example, 70 Gy is delivered in 28 fractions of 2.5 Gy over 5.5 weeks).
Complications of radiation therapy for prostate cancer
The probability of developing post-radiation complications depends on the selected dose, irradiation technique, volume of irradiated tissues and tolerance (radiosensitivity) of healthy tissues exposed to radiation. Acute side effects (during 3-month irradiation) and late radiation complications (occurring within 1 month to 1 year after irradiation) are usually noted. Acute reactions (proctitis, diarrhea, bleeding, dysuric disorders) disappear within 2-6 weeks after the end of irradiation.
Before irradiation, patients are always informed about the risk of late radiation complications of the urinary tract and gastrointestinal tract (GIT), as well as erectile dysfunction. In the European Organization for Research and Treatment of Tumours (EORTT) trial conducted in 1987-1995, 415 patients (90% with T3-4 tumours ) received 70 Gy of radiation therapy; late complications were noted in 377 patients (91%). Moderate complications (changes in the urinary tract and GIT; lymphostasis in the lower limbs) were noted in 86 patients (23%): in 72 patients they were moderate, in 10 patients they were severe, and in 4 patients (1%) they were fatal. Overall, despite the reported fatal outcomes, severe late complications were rare, occurring in less than 5% of patients.
According to a survey of patients, radiation therapy with volumetric planning and intensity modulation causes impotence less often than surgery. A recent meta-analysis showed that the probability of maintaining an erection one year after external beam radiation therapy, cavernous nerve-sparing prostatectomy, and standard surgery is 55%, 34%, and 25%, respectively. When analyzing studies with a follow-up period of more than two years, these figures dropped to 52%, 25%, and 25%, respectively, i.e. the gap between radiation therapy and surgery has increased.