active surveillance

**Definition:** A deliberate, protocol-driven strategy of monitoring a diagnosed cancer with the intent to intervene with curative therapy only if the disease reclassifies or progresses.

**Classic example: low-risk prostate cancer** - Candidates: Grade Group 1 (Gleason 6, 3+3), PSA <10 ng/mL, clinical stage T1c–T2a, low tumor volume (e.g., few cores involved, ≤50% of any core). Selected favorable-intermediate-risk (some Grade Group 2) patients may also qualify per NCCN/AUA. - Monitoring: PSA about every 6 months, DRE about yearly, multiparametric MRI, and confirmatory and periodic repeat biopsies. Genomic tests (e.g., Oncotype DX GPS, Decipher, Prolaris) can add information. - Triggers for definitive treatment: upgrade to Grade Group ≥2 (or higher grade on repeat biopsy), increased tumor volume, rapid PSA rise (short PSA doubling time), clinical or radiographic progression, or patient preference. - Rationale: Many low-grade prostate cancers are indolent. Prostate cancer is overdiagnosed because of PSA screening, and Gleason 6 disease has very low metastatic potential. Treatment carries risks of erectile dysfunction, urinary incontinence, and bowel toxicity. - Evidence: The ProtecT trial compared active monitoring, radical prostatectomy, and radiotherapy. At 10 and 15 years, prostate cancer-specific mortality was very low (about 3% or less) and did not differ significantly among groups. Active monitoring had a higher rate of metastasis and progression, but no difference in overall survival. PIVOT (prostatectomy vs observation) showed no overall survival benefit for surgery in low-risk disease.

**Active surveillance vs watchful waiting (high-yield distinction)** - Active surveillance: curative intent, structured and frequent testing, younger or healthier patients, treatment is triggered by progression. - Watchful waiting: palliative intent, less intensive follow-up, older patients or those with limited life expectancy or significant comorbidities (generally <10 years), treatment (e.g., ADT) given only for symptoms.

**Other applications** - Low-risk papillary thyroid microcarcinoma (<1 cm, no invasion or nodal disease). - Small renal masses (<4 cm), especially in elderly or comorbid patients. - Low-grade, non-muscle-invasive bladder cancer (selected). - DCIS (under study in low-risk trials such as COMET and LORIS). - Asymptomatic or low-tumor-burden follicular lymphoma and CLL ("watch and wait"), where treatment starts only with symptoms or progression. - Barrett esophagus without dysplasia: endoscopic surveillance (a related but distinct use of the term).

**Public health usage (different meaning)** In epidemiology, *active surveillance* means health authorities proactively seek out cases (e.g., contacting providers, labs, or clinics). *Passive surveillance* relies on providers to report cases (e.g., notifiable disease reporting). Active surveillance is more sensitive and more resource-intensive. Examples include polio/AFP surveillance, FoodNet, and outbreak case-finding.

**Boards pearls** - Gleason 6 / Grade Group 1 prostate cancer in a healthy man: active surveillance is an appropriate first-line option. - Don't confuse it with watchful waiting (symptom-driven, palliative). - An upgrade on repeat biopsy or a rising PSA kinetics is the trigger for definitive therapy. - Tradeoff: avoids treatment-related harms, but risks anxiety and a small chance of missed progression.