Adjuvant Radiation Therapy in Node-Positive Prostate Cancer After Radical Prostatectomy
Adjuvant radiation therapy (RT) is not routinely recommended for all node-positive cases after radical prostatectomy (RP), but should be selectively offered to specific high-risk subgroups of patients with lymph node involvement. 1
Patient Selection for Adjuvant RT in Node-Positive Disease
Adjuvant RT should be considered in the following specific scenarios:
Patients with 1-2 positive lymph nodes who also have:
- Pathological Gleason score 7-10 AND
- pT3b/4 disease or positive surgical margins 2
Patients with 3-4 positive lymph nodes, regardless of other pathological features 2
Patients with high risk for progression should receive immediate androgen deprivation therapy (ADT), with consideration of adding RT 1
Evidence Supporting Selective Use of Adjuvant RT
Retrospective data from Da Pozzo et al. showed that in 250 patients with proven pN+ following RP, the addition of RT to hormonal therapy was an independent predictor of:
- Biochemical recurrence-free survival (p=0.002)
- Cancer-specific survival (p=0.009) 1
Briganti et al. performed a matched pair analysis showing that the addition of radiotherapy to ADT appeared to improve cancer-specific and overall survival in node-positive patients 1
The ESMO consensus guidelines classify adjuvant RT added to ADT as a non-standard treatment in pN+ patients (Level of evidence: IV, Strength of recommendation: C) but note it may be considered in selected cases 1
Management Options for Node-Positive Disease
Several options exist for managing node-positive disease after RP:
Androgen Deprivation Therapy (ADT) alone - This is a category 1 option according to NCCN guidelines 1
Observation - This is a category 2A recommendation for very low-risk or low-risk patients but category 2B for patients at intermediate, high, or very high risk 1
Addition of pelvic RT to ADT - This is a category 2B recommendation based on retrospective data showing improved biochemical recurrence-free survival and cancer-specific survival compared with adjuvant ADT alone 1
Treatment Outcomes
Long-term outcomes for prostate cancer patients with lymph node involvement treated with RT show relatively favorable results:
- 10-year overall survival: 78%
- 10-year cause-specific survival: 89% 3
The PLATIN-4 and PLATIN-5 trials demonstrated that salvage RT to the prostate bed and pelvic lymphatic drainage combined with long-term ADT is a curative treatment option with:
- Excellent in-field disease control
- Median progression-free survival of 66 months in PLATIN-4 and 39 months in PLATIN-5
- Low rates (4%) of late grade 3+ genitourinary and gastrointestinal toxicities 4
Potential Side Effects of Adjuvant RT
Patients should be informed about potential toxicities:
- Acute genitourinary toxicity: Grade 1-2: 10.5-26%, Grade 3-4: 2.0-8.0% 1
- Acute gastrointestinal toxicity: Grade 1-2: 22.0-25.0%, Grade 3-4: 0.0-2.0% 1
- Late genitourinary toxicity: Grade 1-2: 2.0-22.0%, Grade 3-4: 0.0-10.6% 1
- Late gastrointestinal toxicity: Grade 1-2: 1.0-12.7%, Grade 3-4: 0.0-6.7% 1
Clinical Considerations and Pitfalls
Timing matters: Adjuvant RT is typically administered within 1 year after surgery 1
Imaging before treatment: Consider restaging evaluation in patients with biochemical recurrence to rule out distant metastases before initiating RT 1
Radiation field: The defined target volumes include the prostate bed; pelvic lymph nodes may be irradiated but pelvic radiation is not universally necessary 1
Common pitfall: Treating all node-positive patients uniformly without considering specific risk factors and number of positive nodes - approximately 25% of node-positive patients may not benefit from adjuvant RT 2
Ongoing clinical trials (RTOG 0534, RTOG 9601, RADICALS, RAVES) will help further clarify the role of adjuvant RT and identify which patients are most likely to benefit 1