New Zealand Prostate Cancer Diagnosis by Age

Fact Check: Most cases of prostate cancer in NZ men - around 69% - are diagnosed in men aged 65 or older

Summary

The quoted figure from the Australian context: “Most cases - around 69% - are diagnosed in men aged 65 or older” modestly overestimates the proportion in NZ.

Based on New Zealand Cancer Registry data (2018-2022), 65.7% of prostate cancer cases are diagnosed in men aged 65 or older on average, with annual figures ranging from 63.2% to 67.7%.

Age is widely considered the single most significant risk factor for prostate cancer.

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Age distribution trends

# Plot age distribution trends over time
ggplot(age_distribution_data, aes(x = year, y = pct_65_plus)) +
  geom_line(linewidth = 1.2, color = "#2E86C1") +
  geom_point(size = 4, color = "#2E86C1") +
  geom_hline(yintercept = 69, linetype = "dashed", color = "#E74C3C", linewidth = 1) +
  geom_text(aes(label = paste0(round(pct_65_plus, 1), "%")), 
            vjust = -1.2, size = 3.5, fontface = "bold") +
  annotate("text", x = 2020, y = 70, label = "Quoted Stat (AU): 69%", 
           color = "#E74C3C", size = 3.5, fontface = "bold") +
  labs(title = "Percentage of Prostate Cancer Cases in Men Aged 65+",
       subtitle = "New Zealand, 2018-2022",
       x = "Year",
       y = "Percentage of cases aged 65+ (%)",
       caption = "Source: Health NZ Cancer Web Tool [@healthnztewhatuoraHealthNZTe2024]") +
  scale_x_continuous(breaks = c(2018, 2019, 2020, 2021, 2022)) +
  theme_minimal() +
  theme(
    plot.title = element_text(size = 14, face = "bold"),
    plot.subtitle = element_text(size = 12)
  ) +
  ylim(62, 72)

Figure 1: Percentage of prostate cancer cases diagnosed in men aged 65+ over time, NZ

Current age distribution

# Create age distribution visualization for 2022
ggplot(age_breakdown_2022, aes(x = age_group, y = percentage)) +
  geom_col(alpha = 0.8, width = 0.7, fill = "#2E86C1") +
  geom_text(aes(label = paste0(round(percentage, 1), "%\n(n=", format(cases, big.mark = ","), ")")), 
            vjust = -0.5, size = 3.5, fontface = "bold") +
  scale_fill_viridis_d(name = "Age Group") +
  labs(title = "Age Distribution of Prostate Cancer Cases (2022)",
       subtitle = paste0("67.7% diagnosed at age 65+ (n=", format(age_65_plus_2022, big.mark = ","), ")"),
       x = "Age Group (years)",
       y = "Percentage of cases (%)",
       caption = "Source: Health NZ Cancer Web Tool [@healthnztewhatuoraHealthNZTe2024]") +
  theme_minimal() +
  theme(
    plot.title = element_text(size = 14, face = "bold"),
    plot.subtitle = element_text(size = 12),
    legend.position = "none"
  ) +
  ylim(0, 50)

Figure 2: Age distribution of prostate cancer cases, NZ 2022.

References

Annual prostate cancer registration data is from the Health NZ Cancer Web Tool (Health NZ (Te Whatu Ora) 2024). Supporting context is provided by New Zealand cancer organizations (Prostate Cancer Foundation NZ n.d.; Te Kahui Matepukupuku o Aotearoa (Cancer Society NZ) 2020). Population estimates are from Stats NZ (Tatauranga Aotearoa (Stats NZ) 16 February 2024, 10:45am).

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Report generated on 2025-09-24 using R version 4.5.1

Health NZ (Te Whatu Ora). 2024. “Health NZ (Te Whatu Ora) Cancer Web Tool.” Shiny {{App}}. Health NZ (Te Whatu Ora) Cancer Data Web Tool. https://tewhatuora.shinyapps.io/cancer-web-tool/.

Prostate Cancer Foundation NZ. n.d. “About Prostate Cancer.” https://prostate.org.nz/prostate-cancer. Accessed September 24, 2025.

Tatauranga Aotearoa (Stats NZ). 16 February 2024, 10:45am. “National Population Estimates: At 31 December 2023 Stats NZ.” https://www.stats.govt.nz/information-releases/national-population-estimates-at-31-december-2023/.

Te Kahui Matepukupuku o Aotearoa (Cancer Society NZ). 2020. “Prostate Cancer.” https://www.cancer.org.nz/cancer/types-of-cancer/prostate-cancer/.