An 82-Year-Old Man with Metastatic Castration-Resistant Prostate Cancer - Episode 2

mCRPC: Monitoring Patients

An expert in prostate cancer discusses the typical follow-up and monitoring approaches for a patient with metastatic CRPC.

Matthew R. Smith, MD, PhD: In my practice, the main state of monitoring is a serial measurement of PSA. Typically, serum PSA is measured every 3 months while [a patient is] on androgen deprivation therapy. Then, in a patient with an appropriate response, as in this case, we would repeat imaging after 1 year to establish a new baseline and to exclude the remote possibility of cancer progression despite a lower, undetectable PSA.

There are a number of metrics that we use to inform decision-making about addition or changes in systemic treatment. Rise in PSA on primary androgen deprivation therapy is the leading indicator of progression to castration-resistant disease, but there's quite a spectrum of what that means with different patients. We consider the time from initiation of ADT [androgen deprivation therapy] to progression as an important indicator about the necessity of adding or intensifying systemic treatment. We consider the rate of PSA rise, or so-called PSA doubling time, in subsequent decisions about adding systemic treatment. PSA doubling time is an established part of decision-making in non-metastatic castration-resistant prostate cancer, where the 3 pivotal studies in that disease state included patients who are at higher risk for progression based on a PSA doubling time of less than 10 months.

Transcript edited for clarity.

Case: A 82-Year-Old Man with Metastatic Castration-Resistant Prostate Cancer

Sept. 2016

Initial presentation

  • A 82-year-old man with nocturia

Clinical workup

  • Abnormal digital rectal exam, PSA 31 ng/mL
  • No family history of prostate cancer
  • Diabetes and hypertension, both of which are managed with medications, neuropathy and uses a cane for long distances
  • Prostate biopsy confirms advanced adenocarcinoma of the prostate and Gleason score of 8 (4 + 4)
  • Bone scans show no detectable spread to bone, abdominal pelvic CT scan shows enlarged pelvic and retroperitoneal nodes consistent with metastatic prostate cancer.
  • His ECOG PS is 1

Treatment

  • Patient starts continuous ADT in October 2016.
  • PSA levels go down to undetectable levels within 3 months after start of treatment. Levels are checked every 3 months thereafter.
  • Patient undergoes repeat abdominal pelvic CT scan after completing a year of therapy which show resolution of pelvic and retroperitoneal nodes.

April 2018

  • An increase in PSA is seen and PSA levels are 2.7 ng/ml, with PSA doubling time of 6 months
  • Patient undergoes conventional imaging with bone scan and CT that show no detectable prostate cancer.
  • PSMA PET scan shows multiple areas of increased uptake in pelvis and retroperitoneum, consistent with previously identified sites of metastasis.
  • Lab tests are normal and patient has adequate liver, renal and bone marrow function.
  • Patient is treated with enzalutamide (160 mg/day) and PSA levels decline
  • After some time on enzalutamide, patient decides to discontinue treatment due to fatigue and problems with gait.
  • Symptoms resolve on their own after going off treatment for a few months
  • Patient is started on darolutamide and continued ADT (leuprolide depot) and remains on this treatment
  • PSA levels stay undetectable on treatment