What is the incidence rate of cancer in a population of 100,000 with 375 new cases diagnosed this year?

Incidence Rate Calculation

The incidence rate is 375 per 100,000 population.

Mathematical Calculation

The incidence rate is calculated by dividing the number of new cases by the population at risk and expressing it per standard population unit (typically per 100,000):

• New cases this year: 300 + 75 = 375 cases
• Population: 100,000 persons
• Incidence rate: (375 ÷ 100,000) × 100,000 = 375 per 100,000 person-years

Context from Cancer Epidemiology

This calculated incidence rate of 375 per 100,000 is substantially higher than most individual cancer types but aligns with aggregate cancer burden data:

• Overall cancer incidence in the United States is approximately 439-497 per 100,000 persons for all cancers combined 1, 2
• Individual cancer examples for comparison:
  • Bladder cancer: 20.4 per 100,000 3
  • Rectal cancer: 15-25 per 100,000 3
  • Pancreatic cancer: 7.3-8.7 per 100,000 3
  • Cervical cancer: 13.2 per 100,000 3
  • Nasopharyngeal cancer: 1.1 per 100,000 3

Important Clarification

The question states "300 new cancer cases diagnosed this year, in addition to 75 new cases in the same year," which mathematically means 375 total new cases. Incidence rate specifically measures new cases only (not prevalent cases), so all 375 cases are appropriately included in the numerator 1, 2.