Prostate cancer cases are getting more serious

The study covered in this summary has been published as a preprint on ResearchSquare.com and has not yet been peer-reviewed.

Key learning points

  • Over the past decade, the incidence of T1a/b prostate cancer has remained stable, but the clinically significant T1a/b disease has increased over time.

  • Across all risk groups and taking into account age and comorbidity status, patients diagnosed with T1a/b prostate cancer are more likely to have active surveillance/watchful wait and less likely to receive definitive treatment with surgery or radiation.

Why this is important

  • Changing recommendations regarding prostate cancer screening in the US over the last decade have led to changes in prostate cancer incidence patterns, and the appropriate treatment of T1a/b prostate cancer is not well defined.

  • Only a few studies have previously treated the incidence of T1a/b prostate cancer. It has remained unclear which patients with T1a/b disease benefit from definitive treatment or watchful waiting.

  • This is the largest study examining trends in incidence, clinical significance and treatment patterns for T1a/b prostate cancer, regardless of risk group, age and comorbidity status.

Study design

  • The National Cancer Database looked at a dataset of 24,679 patients diagnosed with T1a/b prostate cancer between 2010 and 2017.

  • Patients with missing data for pathological T stage, prostate specific antigen (PSA), or Gleason score were removed from the analysis.

  • Clinically significant disease was defined as Gleason grade group ≥ 2.

  • Treatment modalities were assessed for primary treatment only after diagnosis. To reduce treatment bias, a second analysis of the relationships between treatment modalities for patients aged 62 to 68 years was completed. Patients in this age group were eligible for all treatment modalities.

Main results

  • Of the 24,679 identified patients, 15,186 had T1a disease and 9493 had T1b disease.

  • T1a/b prostate cancer represented 3.5% of all prostate cancers with no change in incidence over time.

  • The likelihood of T1a/b prostate cancer being clinically significant increased over time, from 38.8% in 2010 to 44.1% in 2017 (p < .001). Similarly, the odds of being diagnosed with T1a/b non-clinically significant disease decreased from 61.3% in 2010 to 55.9% in 2017.

  • Patients diagnosed with T1a/b disease were significantly older (mean age 72.2 ± 9.6 versus 64.2 ± 8.1; p< .001) than patients diagnosed with T1c disease.

  • Taking age and risk into account, patients with diagnosed T1a/b disease were less likely to receive definitive treatment with surgery or radiation compared to patients with T1c disease (low risk – 6.9% [T1a] vs 17.6% [T1b] vs 67.5% [T1c]† p< .001); (intermediate risk — 21.6% [T1a] versus 30.4% [T1b] vs 86.2% [T1c]† p< .001); (high risk - 28.4% [T1a] vs 26.3% [T1b] vs 78.2% [T1c]† p< .001).

  • Across all risk groups, patients with T1a/b disease were more likely to be actively monitoring/watchful waiting compared to T1c patients. Compared to T1b, patients with T1a disease in all risk groups were more likely to actively monitor/watchful waiting.

Limits

  • Variations between National Cancer Database reporting and coding settings may have affected the data set analyzed.

  • Long-term oncology and functional outcomes were not obtained because the data was not coded in the National Cancer Database.

  • The National Cancer Database only included data for Commission on Cancer accredited facilities and may not be generalizable to other countries.

disclosures

This is a summary of a preprint study, “Trends in Diagnosis and Treatment of T1a, T1b Prostate Cancer in the United States, 2010-2017,” led by Eyal Kord, MD, MPH, Virginia Mason Medical Center, Seattle, Washington, and published on ResearchSquare.com. This research has not yet been peer-reviewed. The full text can be found at ResearchSquare.com.

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