Sandbox:Cancer screening and primary care

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Vishal Devarkonda, M.B.B.S[2]

Epidemiology

The most common type of cancer, excluding non-melanoma skin cancers is breast cancer, with more than 249,000 new cases expected in the United States in 2016. The next most common cancers are lung cancer and prostate cancer. In United states, to qualify as a common cancer, the estimated annual incidence for 2016 had to be 40,000 cases or more.

The following table gives the estimated numbers of new cases and deaths in Unites states for each common cancer type:

American Cancer Society. Cancer Facts & Figures 2016
Cancer Type	Estimated New Cases	Estimated Deaths
Breast	249,200	40,890
Lung (Including Bronchus)	224,390	158,080
Prostate	180,890	26,120
Colon and Rectal (Combined)	134,490	49,190
Bladder	76,960	16,390
Melanoma	76,380	10,130
Non-Hodgkin Lymphoma	72,580	20,150
Thyroid	64,300	1,980
Kidney (Renal Cell and Renal Pelvis) Cancer	62,700	14,240
Leukemia (All Types)	60,140	24,400
Endometrial	60,050	10,470
Pancreatic	53,070	41,780

Adult Cancers

In the U.S. and other developed countries, cancer is presently responsible for about 25% of all deaths. On a yearly basis, 0.5% of the population is diagnosed with cancer. The statistics below are for adults in the United States, and may vary substantially in other countries:

Male		Female
most common (by occurrence)	most common (by mortality)	most common (by occurrence)	most common (by mortality)
prostate cancer (33%)	lung cancer (31%)	breast cancer (32%)	lung cancer (27%)
lung cancer (13%)	prostate cancer (10%)	lung cancer (12%)	breast cancer (15%)
colorectal cancer (10%)	colorectal cancer (10%)	colorectal cancer (11%)	colorectal cancer (10%)
bladder cancer (7%)	pancreatic cancer (5%)	endometrial cancer (6%)	ovarian cancer (6%)
cutaneous melanoma (5%)	leukemia (4%)	non-Hodgkin lymphoma (4%)	pancreatic cancer (6%)

Childhood Cancers

Cancer can also occur in young children and adolescents, but it is rare (about 150 cases per million yearly in the US). Statistics from the SEER program of the US NCI demonstrate that childhood cancers increased 19% between 1975 and 1990, mainly due to an increased incidence in acute leukemia. Since 1990, incidence rates have decreased

The age of peak incidence of cancer in children occurs during the first year of life. Leukemia (usually ALL) is the most common infant malignancy (30%), followed by the central nervous system cancers and neuroblastoma. The remainder consists of Wilms' tumor, lymphomas, rhabdomyosarcoma (arising from muscle), retinoblastoma, osteosarcoma and Ewing's sarcoma. Teratoma is the most common tumor in this age group, but most teratomas are surgically removed while still benign, hence not necessarily cancer.

Female and male infants have essentially the same overall cancer incidence rates, but white infants have substantially higher cancer rates than black infants for most cancer types. Relative survival for infants is very good for neuroblastoma, Wilms' tumor and retinoblastoma, and fairly good (80%) for leukemia, but not for most other types of cancer.

Screening

Breast Cancer

United states preventive services task force recommendations for Breast cancer screening
Population	Recommendation	Grade
Women, 40 Years and Older	The USPSTF concludes that the current evidence is insufficient to assess the additional benefits and harms of clinical breast examination (CBE) beyond screening mammography in women 40 years or older.	I
Women, Age 50-74 Years	The USPSTF recommends biennial screening mammography for women 50-74 years.	B
Women, Before the Age of 50 Years	The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms.	C
Women, 75 Years and Older	The USPSTF concludes that the current evidence is insufficient to assess the benefits and harms of screening mammography in women 75 years and older.	I

Breast cancer screening relevance

Studies have reported that, for women of all age groups with an average risk, breast screening was associated with a reduction in breast cancer mortality of approximately 20%, although there was an uncertainty in the quantitative estimates of outcomes for different breast cancer screening strategies in the United States.

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Colon cancer

United states preventive services task force recommendations for Colon cancer screening
Population	Recommendation	Grade
Adults aged 50 to 75 years	The USPSTF recommends screening for colorectal cancer starting at age 50 years and continuing until age 75 years.	A
Adults aged 76 to 85 years	The decision to screen for colorectal cancer in adults aged 76 to 85 years should be an individual one, taking into account the patient’s overall health and prior screening history. Adults in this age group who have never been screened for colorectal cancer are more likely to benefit. Screening would be most appropriate among adults who 1) are healthy enough to undergo treatment if colorectal cancer is detected and 2) do not have comorbid conditions that would significantly limit their life expectancy.	C

Colon cancer screening relevance

Studies have reported, 40% to 60% lower risk of incident colorectal cancer and mortality from colorectal cancer after screening colonoscopy.

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Cervical cancer

United states preventive services task force recommendations for Cervical cancer screening
Population	Recommendation	Grade
Women 21 to 65 (Pap Smear) or 30-65 (in combo with HPV testing)	The USPSTF recommends screening for cervical cancer in women age 21 to 65 years with cytology (Pap smear) every 3 years or, for women age 30 to 65 years who want to lengthen the screening interval, screening with a combination of cytology and human papillomavirus (HPV) testing every 5 years.	A

Cervical cancer screening relevance

Studies have reported, that in patients undergoing regular cervical cancer, approximately 70%-80% of cervical cancer deaths can be prevented.

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Lung cancer

United states preventive services task force recommendations for Lung cancer screening
Population	Recommendation	Grade
Adults Aged 55-80, with a History of Smoking	The USPSTF recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.	B

Lung caner screening relevance

National lung screen trial (nlst) a randomized controlled trial, involving 50,000 participants as demonstrated a 20% relative lung cancer mortality benefit.

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