Stage

Warning: Be careful when judging the value of early diagnosis with this data.

Net survival rates can change based on how early a cancer is diagnosed, even if the earlier diagnosis did not help the patient. This misleading change is called the lead-time bias. Only use this chapter’s data if you understand its limits.

In an example of lead-time bias, patients A and B both develop cancer when they are 70 and die at 76. There is no difference in years survived after developing cancer.

Figure 5: Lead Time Bias Example
Lead Time Bias Example

However, researchers cannot know when the cancers first developed. Net survival comes from the only two dates known: when the cancer was first detected and when a patient dies. In the example above, A’s cancer is diagnosed one year after developing, meaning A survived five years after diagnosis. B’s cancer is diagnosed three years after developing, meaning B survived only three years after diagnosis. Again, there was no actual difference in outcomes.

Earlier diagnosis can improve net survival rates. According to the National Cancer Institute (2016), treatment can be more effective for some cancers if they are caught before spreading throughout the body. But it’s difficult to know how much of the measured difference is from early diagnosis and how much is from lead-time bias.

Net cancer survival by stage and primary site

Cancers which have spread beyond their original organs are considered late-staged. In this report, survival data for the early stage include cancers which have only spread through their original organs. See the Technical Notes for more details.

Figure 6: 5-year Net Cancer Survival Among Pennsylvanians, Aged 15+, by Stage at Diagnosis and Primary Site

This data is most useful for the types of cancer that can be easily detected by routine screening or going to a physician after spotting symptoms. The United States Preventive Services Task Force (USPSTF) makes recommendations for cancer screening and prevention (2019).

Bladder cancer

Urinary bladder cancer had a larger difference in 5-year net survival between early stage (86.3%) and late stage (26.2%) than other major cancer types. The net survival data for early-staged bladder cancer includes in situ cases, because the language used by doctors makes it hard to determine if a bladder cancer is non-invasive. These in situ cases have good 5-year survival rates. In situ cases were excluded for other cancer types, because they’re known to be non-invasive.

While the USPSTF does not recommend routine screening for urinary bladder cancer, the American Cancer Society recommends patients talk to their physicians if they experience common symptoms (2019b):

  • Blood in urine;
  • Urinating more than usual;
  • Painful or burning feeling while urinating; and
  • Urinating many times during the night.

Even if not caused by cancer, these symptoms usually come with other diseases physicians can help.

Breast cancer

Patients with early-staged diagnoses of breast cancer had 5-year survival rates similar to the general population (98.8% net survival). The observed difference was so small, we cannot be sure if there is an actual difference in risk of death.

Late-staged diagnoses did carry a higher risk of death, with a 5-year rate of 70.3%.

Lung cancer

Of all the cancers for which the USPSTF recommends routine screening, lung and bronchus cancer has the worst net survival. Early-staged lung cancer diagnoses resulted in a 5-year net survival rate of 64.2%, which is close to the late-staged net survival rates of other cancers. For late-staged diagnoses, lung cancer had the fourth lowest 5-year net survival rate, behind esophagus, liver and intrahepatic bile duct, and pancreas cancers. However, the combined number of late-staged diagnoses for those sites was only half of late-staged lung cancer diagnoses in 2017.

Melanoma

The USPSTF does not recommend physicians screen patients for melanoma. However, the ACS (2019a) encourages you to look for new or changing moles, blemishes, or freckles on your skin each month. Catching melanoma at the early stage can limit your extra risk of death (98.0% 5-year net survival). Late-staged melanoma diagnoses have poor outcomes (58.5%).

Prostate cancer

The 5-year net survival rate for Pennsylvanians diagnosed with early-staged prostate cancer was 103.0%. This means they had a lower risk of death than the general population. This report controls for how gender, race, age, and the year affect survival. However, people diagnosed with these early-staged cancers may be healthier than the general population in other ways. If they caught cancer at an early stage because they follow the recommendations for cancer screening, they might have other healthy habits.

Testicular cancer

Like prostate cancer, Pennsylvanians who caught testicular cancer at an early stage had an overall lower risk of death than the general population. Late-staged diagnoses increased the risk of death in the first 2 years after diagnosis but did not affect the risk after that.

Figure 7: Late-Staged Testicular Cancer 5-year Net Survival for Pennsylvanians Aged 15+
Late-Staged Testicular Cancer 5-year Net Survival for Pennsylvanians Aged 15+

Stage distribution

Figure 8: Percentage Distribution of Stage at Diagnosis by Primary Site Among Pennsylvanians, Aged 15+

Stage-specific net survival rates need some other data for context. For example, if we look only at late-staged diagnoses, colorectal cancer had a better 5-year net survival than bladder cancer. But there were 7 times as many late-staged diagnoses of colorectal cancer diagnoses as bladder cancer in 2017.

Two in 5 cancers were diagnosed at a late stage in 2017.

Because leukemia and myeloma occur in blood and platelet cells, nearly all cases (95.4, and 93%, respectively) were considered late stage. For both cancers, certain subtypes can be diagnosed as early, and any cases reported by death certificate alone are of unknown stage.

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