Cancer Screening for Primary Care Physicians: Part I
May 13, 2002 15 minutes read
Cancer Screening for Primary Care Physicians: Part I
Author: Roger J. Zoorob, MD, MPH, Associate Professor, Associate Chair and Residency Program Director, Louisiana State University School of Medicine, Department of Family Medicine, New Orleans, La.
Editor’s Note—Cancer is considered a lethal disease, with a 5-year relative survival rate of 60% for all cancers combined. The National Cancer Institute estimates that 8.9 million Americans currently have cancer. The American Cancer Society estimates that approximately 1,284,900 cases of cancer will be diagnosed in 2002.1 Prevention, early detection, diagnosis, and treatment may prevent premature death or promote decreased incidence of cancer. Primary care physicians (PCPs) are often the first to detect cancer in patients.
This manuscript reviews common cancers encountered in primary care practice. We will review risk factors, primary prevention, early recognition, and screening. We will summarize guidelines and recommendations of national major medical organizations as well as specialty societies, related to different types of cancer.
Colorectal Cancer
Colorectal cancer is a leading cause of cancer mortality in the United States. It is the third most common malignant neoplasm in the world. It is a preventable disease, but most cases are diagnosed at later stages, thus resulting in poor prognoses.2 It is estimated that approximately 148,300 cases of colorectal cancer will occur in the United States in 2002, as well as 56,700 deaths.1
Risk Factors
Risk factors for developing colorectal cancer include the following:3
- A personal or family history of colorectal cancer or adenomatous polyps. Generally speaking, the closer the family relationship and the more family members with these conditions, the higher the risk.
- Hereditary nonpolyposis colorectal cancer (HNCC). Up to 75% of patients with this autosomal dominant syndrome develop a malignancy by the time they reach the age of 65, typically between the ages of 40 and 50.4
- Familial adenomatous polyposis (FAP) including Gardner and Turcot syndromes. Patients with familial adenomatous polyposis often develop colorectal cancer beginning at the age of 40.
- Hamartomas polyposis syndrome, Peutz-Jeghers syndrome, and Juvenile polyposis.
- A personal history of other cancers such as ovarian or breast cancer may increase incidence.
- Inflammatory bowel disease: Patients with ulcerative colitis and, in a less defined manner, Crohn’s Disease, are at increased risk.
- Smoking, alcohol intake, and a high-fat diet that includes red meat.
- Obesity (increases risk, especially excess fat at the waist).
- Age (older than age 50 is an independent risk factor).
Presentation and Diagnostic Findings
Clinical presentation of colon cancer is nonspecific and can mimic other GI diseases. History and physical findings are listed below.5
- Change in bowel habits
- Diarrhea or constipation
- Blood in the stool
- Narrow stool caliber
- Abdominal pain, gas, or discomfort
- Weight loss for no apparent reason
- Iron deficiency anemia
Diagnosis can be made by barium enema, which may show a polyp, mass, or ulcerating lesions. Flexible sigmoidoscopy and colonoscopy, which have the advantage of performing polypectomy and biopsy during the procedure, are also commonly used diagnostic tools.6 Genetic testing should be used if there is a high risk of familial syndromes such as FAP, and possibly HNPCC or other genetic syndromes.7
Primary Prevention
A diet low in fat and high in fiber, fruits, and vegetables can decrease the risk of colorectal cancer, as can smoking cessation and increased physical activity. It is unclear whether calcium intake can also help decrease the chances of developing this type of cancer.8
Nonsteroidal anti-inflammatory drug (NSAID) intake may decrease the risk of colorectal cancer by preventing adenoma formation,8 but no randomized trials have been undertaken, and an appropriate dosage is not yet known.
Celecoxib, a cyclooxygenase-2 inhibitor, was recently approved by the FDA for reducing polyp formation in people with FAP.9
Secondary Prevention and Screening
United States Preventive Services Task Force (USPSTF):10 For average risk patients, an annual Fecal Occult Blood Test (FOBT) is recommended starting at age 50. Sigmoidoscopy, periodicity unspecified, is also recommended. There is no evidence of which modality is better, or if a combination produces any more benefit than either test alone. There is no evidence for or against routine screening with digital rectal exam (DRE), barium enema, or colonoscopy. People who have a family history of hereditary syndromes associated with a high risk of colon cancer should be referred for diagnosis and management.
Canadian Task Force (CTF):11 Average Risk Patients. There is good evidence to support the inclusion of annual or biennial FOBT, and fair evidence to include flexible sigmoidoscopy in patients older than 50 in periodic health examinations. There is insufficient evidence to make recommendations about whether only one, or both should be done. There is also insufficient evidence to include or exclude colonoscopy as an initial screening mechanism in periodic health examinations.
High Risk Patients. There is fair evidence to support either genetic testing, or flexible sigmoidoscopy for patients at risk for familial polyposis, and screening with colonoscopy for individuals with an above-average risk of hereditary nonpolyposis colon cancer (HNPCC), or a family history (first-degree relative) of polyps or colorectal cancer.
American Cancer Society (ACS):12 At age 50, start yearly FOBT or flexible sigmoidoscopy every 5 years (both are preferred). Other strategies include a double contrast barium enema every 5 years, or colonoscopy every 10 years. Earlier and more frequent screening is recommended for those at high risk, including those with: a personal history of hereditary colorectal cancer syndromes or adenomatous polyps; a strong family history of colorectal cancer or polyps (cancer or polyps in a first-degree relative younger than 60 or in 2 first-degree relatives of any age); or a personal history of chronic inflammatory bowel disease. The schedule recommended by the ACS is in Table 1.
National Cancer Institute (NCI):13 Fecal occult blood testing (FOBT) annually or biennially between the ages of 50 and 80 decreases mortality from colorectal cancer. Regular screening by sigmoidoscopy in people older than 50 years old may decrease mortality from colorectal cancer, but there is insufficient evidence to designate an interval for such screening.
American College of Physicians (ACP):14 Screening with FOBT reduces mortality rates associated with colorectal cancer, but an optimal frequency has not been determined.15 Complete colonoscopy is preferred as an evaluation method, with a possible alternative being flexible sigmoidoscopy and an air contrast barium enema. Screening with FOBT reduces colon cancer mortality by 15-35%. Sigmoidoscopy reduces mortality by 30-60% if the lesion can be reached by the sigmoidoscope.
American Academy of Family Physicians (AAFP):16 Adults 50 years and older should be screened for colorectal cancer with FOBT (annually), sigmoidoscopy, colonoscopy, or barium enema. Adults with a family history of early colorectal cancer should have an FOBT (annually), sigmoidoscopy, barium enema or colonoscopy beginning at age 40.
The American College of Gastroenterology (ACG):17 If resources, expertise, or reimbursement are not available, then a sigmoidoscopy is recommended every 5 years with a fecal occult blood test (FOBT) annually. The ACG indicates that individuals with a positive family history are at high risk. For patients with single first-degree relatives with cancer diagnosed at aged 60 or older, screening should begin at the age of 40, preferably by colonoscopy every 10 years. For patients with single first-degree relatives (who are diagnosed with cancer younger than the age of 60) or who have multiple first-degree relatives (with any type of cancer diagnosed at any age) screening should begin at the age of 40, or 10 years younger than the age of diagnosis of the youngest affected relative, whichever comes first. Preferably these patients should be screened by colonoscopy every 3-5 years.17
Lung Cancer
Lung cancer is the most frequent cause of cancer mortality in the world. According to the ACS, there were 164,100 new cases of lung cancer in the United States in the year 2000; and an estimated 169,000 cases will be diagnosed in 2002 with 154,900 deaths. This accounts for 28% of all cancer deaths in this country.1 Lung cancer presents a major health problem because patients do not develop symptoms until late in the course of the disease.
Lung cancer used to be a male-only disease, but now incidence is rising in women because of increased smoking.18 Survival rates for lung cancer are lower than other cancers in general. The average 5-year survival rate for localized lung cancer is 48%; overall it is 14.5%.1
Risk Factors
Smoking causes 87% of lung cancer. Many of the 4000 different chemicals in cigarette smoke are carcinogens. Naturally occurring radon in homes is another cause of lung cancer, and the Environmental Protection Agency estimates that 8 million US homes have unacceptable radon levels.19 The third most common cause is occupational exposure to asbestos, especially when people work with insulation materials and perform automobile brake repair.20
Presentation and Diagnostic Findings
Lung cancer can present commonly as an incidental silent mass on a chest x-ray (CXR). Some of the symptoms are cough, weight loss, fever, hemoptysis, hoarseness, chest pain, wheezing, and shortness of breath. A CXR may show a lung mass, lung nodule, or pleural effusion. Bronchoscopy, CT scan and pleural tap or biopsies are modalities that may aid in diagnosis and obtain tissue for ultimate pathologic diagnosis.
Primary Prevention
Smoking cessation is the mainstay of primary prevention. A 30-50% reduction in lung cancer mortality risk occurs 10 years after smoking cessation.21 Avoidance of both direct and second-hand smoke is important.
It is important to note that pharmacological doses of beta-carotene increase lung cancer incidence and mortality in heavy smokers. Two studies have contributed to this evidence: The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Trial (ATBC Trial) and the Beta Carotene and Retinol Efficacy Trial (CARET). In the ATBC Trial, 18% more lung cancers were diagnosed and 8% more overall deaths occurred in study participants taking beta-carotene. In CARET, after an average of 4 years of receiving supplements, 28% more lung cancers were diagnosed and 17% more deaths occurred in participants taking beta-carotene and vitamin A than in those taking placebos.22
Secondary Prevention and Screening
USPSTF:23 Routine screening for lung cancer using CXR or sputum cytology in asymptomatic people is not recommended.
CTF:24 There is fair-to-good evidence to exclude sputum cytology and CXR for asymptomatic people in period health examinations.
ACS:25 CXRs and sputum cytology have not proven to reduce mortality from lung cancer. Spiral or helical low-dose CT scanning and molecular markers in sputum showing some promise and are being evaluated. Prophylactic chemotherapy is not yet established in standard practice but is currently under study.
NCI:26 Screenings with chest x-ray and/or sputum cytology have not been supported by randomized controlled trials; none have demonstrated a reduction in lung cancer mortality. The current evidence does not support lung cancer screening.
AAFP:27 For asymptomatic individuals, use of CXR and/or sputum cytology is not recommended.
Skin Cancer
The skin is the largest organ in the body; hence skin cancer is the most common form of cancer. It accounts for more than 40% of all cancers. Skin cancer is divided into 2 types: melanoma and nonmelanoma. The ACS estimates that about 2200 people will die from nonmelanoma skin cancer this year. Since most nonmelanoma skin cancer is nonlethal, it is not reportable to cancer registries. Still, about 1.3 million cases of nonmelanoma are estimated to occur each year in the United States.1
Nonmelanoma skin cancer is predominantly of 2 types: basal cell and squamous cell. Both develop on sun-exposed areas. Melanoma, on the other hand, is the most serious and rapidly increasing form of skin cancer, and causes approximately 75% of all skin cancer deaths.28
Estimates by the ACS show that 53,600 new cases of melanoma in the United States are expected in 2002 and 7400 deaths.1
Risk Factors
Nonmelanoma Skin Cancer: High exposure to sunlight and other forms of ultraviolet (UV) light such as tanning lamps increases the risk of nonmelanoma skin cancer.29 In addition, men are 2-3 times more likely to develop this type of cancer than women. Radiation exposure is also a risk factor. Fair-skinned people are 20 times more likely to develop it compared to African-Americans. Less common risk factors are treatment of psoriasis with UV light, scars, exposure to heavy metals, and basal nevus syndrome.
Melanoma: Moles are the most important risk factor for melanoma, especially the dysplastic nevus. Dysplastic nevi run in families. Other types of moles placing patients at higher risk are the congenital melanocytic nevi, especially the larger ones. The risk of melanoma developing in congenital melanocytic nevi is more than 5%. Fair skin raises the risk for melanoma to the same degree as for nonmelanomas. Other risk factors are family history, excessive exposure to UV radiation (eg, sunbathing),30 and being older than age 50. Patients on immune suppressive therapy as well as those who suffer from xeroderma pigmentosum, a rare inherited condition, are also at higher risk for melanoma.31
Presentation and Diagnostic Findings
Nonmelanoma Skin Cancer: Skin cancer presents as a change on the skin, especially a new growth or a sore that will not heal, especially for longer than 2 weeks. Although most skin cancers are painless, they do not all look the same. Both basal and squamous cell cancers are found mainly on areas of the skin that are exposed to the sun (eg, head, face, neck, hands, arms). A skin cancer may look like a lump, perhaps small, smooth, shiny, or waxy. It can also appear firm, begin to bleed, or develop a crust. Skin cancer can also start as a flat, scaly, dry red spot.32
Melanoma: The first sign is any change in an existing mole. Changes to look for follow the tumor ABCD acronym. Hence, look for Asymmetry, Border changes or irregularity, Color change, and Diameter change, usually an increase in size. Melanomas are usually 5 mm or more in size. Diagnosis is usually confirmed by performing an excisional biopsy.32
Primary Prevention
The American Academy of Dermatology (AAD) advises individuals to practice a comprehensive sun protection program that includes avoiding outdoor activities between 10 am and 4 pm, when the sun’s rays are the strongest, and seeking shade whenever possible. It is also advisable to wear protective clothing and a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15.33
The ACS also recommends the same, adding to avoid sunburn, especially in children, to prevent future melanomas. For melanoma, it is also necessary to identify abnormal moles and remove them.34
The NCI, CTF, and USPSTF share the same recommendations as the AAD and the ACS except they point out that there is poor evidence to include or exclude the use of sunscreen in the prevention of melanoma and nonmelanoma skin cancers.
Secondary Prevention and Screening
USPSTF:35 There is insufficient evidence to recommend for or against total body screening in the early detection of melanoma or nonmelanoma skin cancers. The benefits of screening are unproven even in high-risk patients. However, physicians should be alert for lesions with malignant features (ie, ABCD features) when doing a physical examination for other purposes.
CTF:36 Guidelines were adapted (see Table 2) from material prepared by USPSTF. There is poor evidence to include or exclude total skin examination by a health care professional or self skin examination in early detection of skin cancer. There is fair evidence, however, to perform a total skin examination in high-risk individuals (eg, those with family melanoma syndrome).
ACS:34 A cancer-related checkup, including a skin examination, should be performed every 3 years for people between 20 and 40 years of age, and every year for anyone age 40 and older. Self-examination of the skin should be conducted regularly following the ABCD for melanoma.
NCI:35 There is insufficient evidence to establish whether a decrease in mortality occurs with routine examination of the skin.
AAFP:36 In asymptomatic people, there is insufficient evidence on which to make a recommendation for or against routine screening for skin cancer.
References
1. American Cancer Society. Statistics for Cancer. Cancer Facts & Figures 2002. http://cancer.org/downloads/STT/CFF2002.pdf. (Accessed 02/25/02).
2. Dove-Edwin I, Thomas HJ. Review article: The prevention of colorectal cancer. Aliment Pharmacol Ther. 2001;15:323-336.
3. Borum ML. Colorectal cancer screening. Prim Care. 2001; 28:661-674.
4. Read TE, Kodner IJ. Colorectal cancer: Risk factors and recommendations for early detection. Am Fam Physician. 1999;59:3083-3092. Review.
5. National Cancer Institute. Cancer Facts. Questions and Answers About Screening, Early Detection, and Treatment for Colorectal Cancer. http://cis.nci.nih.gov/fact/6_32.htm. (Accessed 02/21/02).
6. Araujo SE, Alves PR, Habr-Gama A. Role of colonoscopy in colorectal cancer. Rev Hosp Clin Fac Med Sao Paulo. 2001;56:25-35.
7. Giardiello FM, Brensinger JD, Petersen GM. AGA technical review on hereditary colorectal cancer and genetic testing. Gastroenterology. 2001;121:198-213.
8. National Cancer Institute. Cancer.gov. Colorectal Cancer (PDQ®) Prevention. www.nci.nih.gov/cancer_information/doc_pdq.aspx?version=provider&viewid=be505c0c-0f17-460f-ae0a-e567ca9bc6b2#15 (Accessed 02/21/02).
9. Steinbach G, Lynch PM, Phillips RK, et al. The effect of celecoxib, a cyclooxygenase-2 inhibitor, in familial adenomatous polyposis. N Engl J Med. 2000;342:1946-1952.
10. Screening. Colorectal Cancer. U.S. Preventive Services Task Force 1996. www.ahcpr.gov/clinic/uspstf/uspscolo.htm. (Accessed 03/07/02).
11. Colorectal cancer screening. Recommendation Statement from the Canadian Task Force on Preventive Health Care. CMAJ. 2001;165:206-208.
12. American Cancer Society. Prevention and Early Detection. ACS Cancer Detection Guidelines. Colon and Rectum. http://cancer.org/eprise/main/docroot/PED/content/PED_2_3X_ACS_Cancer_Detection_Guidelines_36?sitearea=PED. (Accessed 03/14/03).
13. NCI Cancer.gov. Colorectal Cancer (PDQ®): Screening. www.nci.nih.gov/cancer_information/doc_pdq.aspx?version=provider&viewid=d5d1df96-c862-43af-86bc-f80466b57966. (Accessed 02/22/02).
14. ACP-ASIM Annals of Internal Medicine. Position Papers. Clinical Guideline: Part I. Suggested Technique for Fecal Occult Blood Testing and Interpretation in Colorectal Cancer Screening. www.acponline.org/journals/annals/15may97/ppcolo1.htm (Accessed 03/15/02).
15. Suggested technique for fecal occult blood testing and interpretation in colorectal cancer screening. American College of Physicians. Ann Intern Med. 1997;126:808-810.
16. American Academy of Family Physicians. Periodic Health Examinations. Summary of AAFP Policy Recommendations and Age Charts. Recommend General Population and Recommend Specific Population http://aafp.org/exam (Accessed 03/15/02).
17. American College of Gastroenterology. Colorectal Cancer Screening Recommendations. www.acg.gi.org/acg-dev/patientinfo/frame_coloncancer.html. (Accessed 03/15/02).
18. Fauci AS, Braunwalk, Issebbacken KJ, et al, eds. Hemotology and oncology. In: Harrison’s Principles of Internal Medicine. 14th ed. New York, NY: McGraw-Hill Health Professionals Division; 1998:552-556.
19. Frumkin H, Samet JM. Radon. CA Cancer J Clin. 2001;51: 337-344.
20. NCI Cancer Facts. Asbestos Exposure: Questions and Answers. http://cis.nci.nih.gov/fact/3_21.htm (Accessed 02/20/02).
21. Kattapong VJ, Locher TL, Secker-Walker RH, American College of Preventive Medicine practice policy. Tobacco-cessation patient counseling. Am J Prev Med. 1998;15:160-162.
22. The National Cancer Institute. Cancer Facts. Questions and Answers About Beta Carotene Chemoprevention Trials. http://cis.nci.nih.gov/fact/4_13.htm. (Accessed 03/15/02).
23. Screening. Lung Cancer. U.S. Preventive Services Task Force 1996. www.ahcpr.gov/clinic/uspstf/uspslung.htm. (Accessed 03/012/02).
24. Canadian Task Force on Preventive Health Care. Summary Table of Recommendations. Interventions Other than Smoking Cessation to Prevent Lung Cancer. www.ctfphc.org. (Accessed 02/19/02).
25. American Cancer Society. Prevention and Early Detection. Can Lung Cancer be Found Early? http://cancer.org/eprise/main/docroot/CRI/content/CRI_2_4_3X_Can_lung_cancer_be_found_early_26?sitearea=CRI. (Accessed 03/12/02).
26. NCI Cancer.gov. Lung Cancer (PDQ®): Screening. www.cancer.gov/cancer_information/doc_pdq.aspx?version=provider&viewid=a180f2d0-1c43-4899-9f92-bb858aa76e8d. (Accessed 02/29/02).
27. Summary of AAFP Policy Recommendations and Age Charts. Recommend Against (No Strength Implied). www.aafp.org/exam/ra.html (Accessed 03/15/02).
28. Centers for Disease Control. MMWR Morb Mortal Wkly Rep. Notice to Readers: National Melanoma/Skin Cancer Detection and Prevention Month —May 2001. www.cdc.gov/mmwr/preview/mmwrhtml/mm5018a4.htm. (Accessed 02/26/01).
29. Chuang TY, Brashear R. Risk factors of non-melanoma skin cancer in United States veterans patients: A pilot study and review of literature. J Eur Acad Dermatol Venereol. 1999; 12:126-132.
30. Marks R. Epidemiology of melanoma. Clin Exp Dermatol. 2000; 25:459-463.
31. American Cancer Society. Cancer Reference Information. What Are The Risk Factors for Melanoma. http://cancer.org/eprise/main/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_for_melanoma_50?sitearea=CRI (Accessed 02/2002).
32. National Cancer Institute. Cancer.gov. What You Need to Know About Melanoma. www.nci.nih.gov/cancer_information/doc_wyntk.aspx?viewid=8f3e1c39-1ba0-4a7e-9088-e03c592c5395. (Accessed 02/19/02).
33. American Academy of Dermatology. Patient Information. American Academy of Dermatology Urges the Public to Practice Sun Safety-Long-Standing Studies Support UVB Radiation is a Leading Cause of Skin Cancer. www.aad.org/PressReleases/UVBRadiation.html (Accessed 03/27/02).
34. American Cancer Society. Prevention and Early Detection. Can Melanoma Be Prevented? www.cancer.org/eprise/main/docroot/CRI/content/CRI_2_4_2x_Can_Melanoma_Be_Prevented_50?sitearea=PED (Accessed 2/26/02).
35. Screening. Skin Cancer. U.S. Preventive Services Task Force 1996. www.ahcpr.gov/clinic/uspstf/uspsskca.htm (Accessed 02/20/02).
36. Canadian Task Force on Preventive Health Care. Full Text Review. Prevention of Skin Cancer. www.ctfphc.org (Accessed 03/04/02).
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