1 Counting cancers

1.1 Cancer experiences: a personal view

In 60 years of life I have been cancer-free, but many family members and friends have had to address the disease.

I prepared a table with some information on contacts whose cancer experiences I know of:

datatable(vjc_cancer_net)

Note that the table can be sorted and searched. You can also alter the number of records presented.

1.1.1 Questions

A.1.1. Why would a person make a table like this?

A.1.2. How could this table be made more informative?

1.2 Cancer rates and public health

Motivations for studying cancer at the population level are detailed on a National Cancer Institute web page.

Briefly, cancers contribute to

years of life lost
loss of quality of life for patients and families
lost productivity

Furthermore, as the population ages, the effects of cancer will be more pronounced as time goes on.

Although cancer affects individual patients and their families in different ways, studying its impact on large populations can provide important information that influences practices, policies, and programs that directly affect the health of millions of people in the United States each year. – from the NCI web page

This idea of “studying [cancer’s] impact on large populations” brings us immediately to data science and statistics.

Two terms of epidemiology will be of use to us

prevalence: the proportion of the population currently affected by a disease
incidence: the proportion of the population, in a given time interval, that was disease-free prior to the interval but developed the disease within the interval

Prevalence expresses the current burden of disease within a population.

Incidence expresses the rapidity with which a disease grows in a population.

For a more detailed discussion of these terms, check this CDC site.

An excellent resource on rate estimation and interpretation is the online book on cancer screening by Pamela Marcus, hosted at NCI.

1.2.1 Collecting cancer data

The role of statistics in our lives has intensified with the COVID-19 pandemic.

Policymakers have proposed that personal protective behaviors and legal obligations to mask or avoid traveling can change depending on the “infection rates” in localities.

Cancer Registries are systems managed at the state level that collect information on cancers as they are identified by health care providers.

“SEER” stands for Surveillance, Epidemiology and End Results. It is a program developed at the National Institutes of Health (NIH) National Cancer Institute (NCI). Data are collected at 17 regional centers.

The SEER web site, offers various facets of cancer data to investigate.

1.2.2 Body sites with relatively high cancer incidence

1.2.3 New diagnoses, and deaths, over time

A very broad overview of cancer’s impact on Americans over the past 20 years:

1.2.4 Exercises

A.2.1 The display just above asserts that over 1.8 million Americans will present with a new cancer diagnosis in 2021. Re-express this prediction as a “rate per 100,000 persons”.

A.2.2 True or False: Of cancers newly identified in US citizens in 2021, more than 8% arise in the pancreas.

1.3 A view of pancreatic cancer incidence

We can “drill down” on specific cancer types using the drop-down menu at seer.cancer.gov. For cancer of the pancreas we have:

[SEER pancreas, 2021](https://github.com/vjcitn/YESCDS/blob/main/man/figures/pancreas.jpg?raw=true

1.4 A view of colorectal cancer incidence

For cancer of the colon or rectum we have:

1.4.1 Exercises

A.2.3 Which of the following describes observations on pancreatic cancer between 1992 and 2019?

the death rate per 100000 population increased by two,
the rate of new pancreatic cancers per 100000 population increased by two,
the rate of new pancreatic cancers per 100000 population remained stable.

A.2.4 True or false: The death rate, and the incidence rate, for cancers of colon and rectum were approximately halved in the interval between 1992 and 2019.

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1.5 Monitoring of cancer by public health institutions

1.5.1 County-level variation in cancer rates

We focus on colorectal cancer:

1.5.2 Exercises

A.3.1 Use State Cancer Profiles to produce a map of colorectal cancer incidence for Massachusetts. You will have to make selections in the web interface. Choose the Quantiles interval type with 8 intervals. Obtain the map for both sexes, all ages. What is the county with lowest incidence of colorectal cancer?

A.3.2 True or false: In Massachusetts, the age-adjusted incidence of colorectal cancer for individuals greater than 65 years of age is approximately ten times that of individuals less than 50 years of age.

A.3.3 Return to cancers of colon and rectum. Form a map for Area “United States”, Area Type “By State”. Limit to age less than 50. Which state has the highest incidence of colorectal cancer in this age group?

A.3.4 Data presented by the Environmental Protection Agency can be seen at Exhibit 5 of the current Report on the Environment. What is the estimated incidence rate for colorectal cancer for females in 2017 (end of the curve)? How does this compare to the “State Cancer Profile” statistic for females of all ages?

A.3.5 Using the EPA chart in Exhibit 5, which type of cancer in females shows a steady decrease in incidence from 2000 to 2017?