What is the next step in management for a 79-year-old man with intermediate risk prostate cancer treated with Intensity-Modulated Radiation Therapy (IMRT) and a rising Prostate-Specific Antigen (PSA) trend?

Management of Rising PSA in a 79-Year-Old Man with Intermediate Risk Prostate Cancer Post-IMRT

Androgen deprivation therapy (ADT) with a GnRH agonist such as goserelin is the recommended next step for this patient with biochemical recurrence after radiation therapy, given the significant PSA rise from 0.6 to 2.2 over one year.

Assessment of Biochemical Recurrence

• The patient's PSA trend (0.6 → 1.8 → 2.2) over one year represents biochemical recurrence after IMRT, as it shows three consecutive rises in PSA 1
• The current PSA value of 2.2 ng/mL exceeds the threshold of 1.5 ng/mL that is commonly used to define biochemical failure after radiation therapy 1
• The rapid rise in PSA (more than tripling in one year) suggests an aggressive pattern of recurrence that warrants intervention 1

Risk Stratification Considerations

• At 79 years of age with intermediate risk prostate cancer and a rapidly rising PSA, this patient has a significant risk of developing metastatic disease if left untreated 1
• PSA doubling time (PSA-DT) is a critical prognostic factor in biochemical recurrence; shorter doubling times correlate with higher risk of metastatic progression and prostate cancer-specific mortality 1
• The patient's PSA pattern shows a concerning velocity that suggests a relatively short PSA-DT, placing him at higher risk for clinical progression 2

Treatment Recommendations

First-Line Approach:

• Initiate androgen deprivation therapy (ADT) with a GnRH agonist such as goserelin 3
• Goserelin has demonstrated efficacy in advanced prostate cancer with PSA falls at three months of 94% in clinical trials 3
• Hormonal therapy has been shown to delay metastatic progression in patients with rising PSA 1

Monitoring Recommendations:

• After initiating ADT, monitor PSA levels every 3 months to assess treatment response 1
• Periodic monitoring of serum testosterone levels should be considered if the anticipated clinical or biochemical response to treatment has not been achieved 3
• Regular imaging studies should be performed to evaluate for development of metastatic disease 1

Clinical Considerations and Caveats

• While some clinicians might consider observation in an elderly patient, the rapid PSA rise in this case suggests active disease that warrants intervention to prevent morbidity from metastatic progression 4
• Treatment with ADT may be associated with side effects including decreased bone mineral density, metabolic changes, and cardiovascular risks that should be discussed with the patient 3
• Quality of life considerations are important, as ADT can cause hot flashes, sexual dysfunction, and fatigue 2
• The patient should be monitored for potential complications of ADT including diabetes or loss of glycemic control, cardiovascular events, and decreased bone mineral density 3

Alternative Approaches

• For patients who are not candidates for or decline ADT, antiandrogen monotherapy could be considered as an alternative with potentially fewer side effects 2
• Clinical trials evaluating novel agents for non-metastatic biochemical recurrence may be available and could be considered 1
• Observation might be appropriate for patients with very slow PSA kinetics or significant comorbidities limiting life expectancy, but is not recommended for this patient given the rapid PSA rise 4

By initiating ADT promptly in this patient with biochemical recurrence after IMRT, the goal is to delay metastatic progression and potentially improve prostate cancer-specific survival while maintaining quality of life.