Reviews

Detecting cancer: Pearls for the primary care physician

Author and Disclosure Information

ABSTRACTFive-year survival rates have improved over the past 40 years for nearly all types of cancer, partially thanks to early detection and prevention. Since patients typically present to their primary care physician with initial symptoms, it is vital for primary care physicians to accurately diagnose common cancers and to recognize unusual presentations of highly curable cancers such as Hodgkin lymphoma and testicular cancers, for which the 5-year overall survival rates are greater than 85%. This paper reviews these cancers and provides clinically relevant pearls from an oncologic perspective for physicians who are the first point of contact.

KEY POINTS

  • By detecting breast cancer lesions 2 years before they are discovered by clinical breast examination, mammography has been found to reduce the mortality rate from breast cancer.
  • In the United States, 20% of colorectal cancer patients have distant metastases at the time of diagnosis. The most common sites are the lymph nodes, liver, lungs, and peritoneum.
  • The patient should fully understand the risks and benefits of prostate-specific antigen (PSA) screening and that it is controversial because, since the advent of PSA testing, the lifetime risk of being diagnosed with prostate cancer has increased, but the lifetime risk of dying from it has remained the same.


 

References

According to the Surveillance, Epidemiology, and End Results database, 5-year overall survival rates have improved for nearly all tumor types during the past 40 years.1 This has been accomplished with better treatment and earlier detection of the most common cancers, as well as the uncommon but highly curable tumor types.

Primary care physicians play a vital role in detecting cancers at earlier stages and synthesizing information from a patient’s presentation, vital signs, physical examination, and results of laboratory and radiographic testing. Yet cancers can be easily overlooked, and highly curable cancers such as Hodgkin lymphoma and testicular cancer, with 5-year survival rates above 85%, can have unusual presentations. Aside from the obvious health consequences, missed cancer diagnoses are often the subject of malpractice suits.

This paper reviews cancers that are easily missed and provides clinically relevant pearls from an oncologic perspective for primary care physicians, who are generally the first point of contact for patients.

BREAST CANCER DETECTION AND SCREENING

Breast cancer is the second most common cause of cancer death in US women and the most common cause of death in US women ages 20 to 59 (Table 1).2–4

Screening mammography has had a significant impact on early detection rates, and this has translated into a 20% to 30% decrease in the breast cancer mortality rate.5,6 But despite national screening guidelines, up to 15% of cases are diagnosed on the basis of a palpable breast mass not detected on mammography, and 30% are diagnosed with a breast mass during the interval between mammograms.5,6 Moreover, delay in breast cancer diagnosis is one of the most common reasons for malpractice suits.7,8

Warning signs

Breast cancer can present clinically as a single, dominant, indurated mass with irregular borders. The mass can have associated ecchymosis, erythema, nipple discharge, nipple retraction, and nipple eczema.9,10 Pay close attention to any history of breast trauma, pain, signs or symptoms suggestive of local infection, and the lesion’s relationship to the patient’s menstrual cycle. Locally advanced disease typically presents with axillary adenopathy, as well as skin findings such as erythema, thickening, and dimpling.

Initial imaging workup for a breast mass

Women presenting with a breast mass should undergo breast imaging, followed by core needle biopsy of any suspicious abnormality. Depending on the clinical breast examination and the interpretation of the mammogram, as reported as a Breast Imaging Reporting and Data System (BIRADS) score, ultrasonography, magnetic resonance imaging, or biopsy may be the next course of action. Ultrasonography is recommended in evaluating masses in women who are under age 30 (who are more likely to have dense breasts that make standard mammography difficult to interpret) or who are pregnant (because it does not involve radiation).

For patients with a borderline or indeterminate clinical examination (eg, asymmetric skin-thickening or discoloration, nipple discharge or inversion, nodularity, finding on imaging [ie, BIRADS 3 lesion]), closer follow-up with repeat or additional imaging or biopsy, or both, is strongly recommended.

Screening recommendations vary

The age at which to start breast cancer screening has been a matter of debate in recent years, and different organizations have different recommendations (Table 2).11–13 According to the American Cancer Society (ACS), women should begin screening mammography at age 45 and should continue it indefinitely as long as they are in good health.11 This guideline is in line with those of the National Comprehensive Cancer Network (NCCN)12 but differs from those of the US Preventive Services Task Force (USPSTF).13

One reason for the controversy is that although starting screening at a younger age may allow for earlier detection, it also leads to overdiagnosis and to unnecessary tests and procedures. However, the NCCN noted limitations in studies looking at the overdiagnosis of breast cancer, including their use of incidence data from the 1970s, which not only underestimated the annual incidence of breast cancer in the United States, but also neglected to differentiate invasive cancer from ductal carcinoma in situ.12 Additionally, by detecting breast cancer lesions 2 years before they are discovered by clinical breast examination, mammography has been found to reduce the mortality rate from breast cancer.14

The frequency of mammography should be individualized and should involve not only an assessment of the patient’s risk factors (eg, age, family history, genetic predisposition, history of precancerous lesions, history of radiation exposure) but also a discussion of the benefits, limitations, and potential harms of screening. Both the ACS and the NCCN recommend yearly mammography for women ages 45 to 54. For those age 55 and older, the ACS recommends screening mammography every 2 years until the patient’s life expectancy is less than 10 years, whereas the NCCN recommends yearly screening mammography indefinitely. Meanwhile, the USPSTF recommends mammograms every 2 years for women ages 50 to 74.

Pearls

  • Pay close attention to a history of breast trauma, pain, and signs of infection.
  • Consider ultrasonography for women under age 30, who are more likely to have dense breasts.

COLORECTAL CANCER

With an estimated annual incidence of 132,700 cases diagnosed in the United States in 2015, colorectal cancer is the third most common cancer.

National guidelines that recommend colonoscopy (starting at age 50 for people at standard risk) have had a significant impact on early detection rates and have translated into a significant decrease in mortality rates.2,15,16 However, a missed diagnosis of colorectal cancer is one of the most common reasons for malpractice suits, typically because the patient was not referred for colonoscopy according to national guidelines.17–19

Symptoms depend on tumor location

In symptomatic cases, clinical manifestations differ depending on tumor location.

Left-sided tumors can present with hematochezia, colicky abdominal pain, and a change in bowel habits. And because the descending (left) colon has a smaller lumen than the right and tumors typically are annular in shape, left-sided cancers may present with abdominal distention with or without bowel obstruction or nausea and vomiting.

Right-sided tumors typically present with iron deficiency anemia from unrecognized blood loss.

Tumors near the rectum can cause tenesmus, rectal pain, and diminished caliber of stools.

In the United States, 20% of colorectal cancer patients have distant metastases at the time of diagnosis, and the most common sites are the lymph nodes, liver, lungs, and peritoneum.17

Uncommon presentations of colorectal cancer include pneumaturia, fecaluria or recurrent urinary tract infection from a fistula, bacteremia with Streptococcus bovis or Clostridium septicum, and intra-abdominal abscess from a localized bowel perforation.20,21

Initial workup

Once cancer is suspected, colonoscopy is the most accurate and versatile diagnostic test. It not only permits localization and biopsy of lesions throughout the large bowel, but also detects synchronous neoplasms and permits removal of polyps. Computed tomographic (CT) colonography is an alternative if colonoscopy is contraindicated, but it can only detect larger (ie, > 6-mm) tumors.22

According to the ACS,23 men and women at average risk should undergo colorectal cancer screening beginning at age 50. ACS screening recommendations for polyps and colorectal cancer include flexible sigmoidoscopy every 5 years, colonoscopy every 10 years, double-contrast barium enema every 5 years, or CT colonography every 5 years. Tests that detect cancer but not polyps include guaiac-based fecal occult blood test (every year), fecal immunochemical test (every year), stool DNA test (every 3 years). These recommendations are fairly consistent with those of the NCCN12 and USPSTF24 (Table 3).12,23,24

Pearls

  • Uncommon presentations include urinary tract problems and intra-abdominal abscess.
  • CT colonography can only detect larger tumors.

PROSTATE CANCER

With an estimated 220,800 cases and 27,540 deaths in 2015, prostate cancer is the most common cancer and the second most common cause of cancer-related death in US men.2 Widespread use of serum prostate-specific antigen (PSA) testing has increased the rate of detection of prostate cancer.

Signs and symptoms

Most men with early-stage prostate cancer have no symptoms directly attributable to the disease.

Obstructive symptoms such as hesitancy, decreased stream, retention, and nocturia are common but are usually related to concomitant benign prostatic hypertrophy. As in prostatitis, patients with prostate cancer may present with irritative symptoms such as urinary frequency, dysuria, and urgency.

Patients who present with locally advanced prostate cancer may have symptoms secondary to local invasion, such as hematuria, hematospermia, and new-onset erectile dysfunction.

Prostate cancer usually metastasizes to bone, most commonly to the vertebrae and sternum, and the associated pain can be acute or insidious.

Diagnosis

Prostate cancer is most often diagnosed after biopsy prompted by an elevated PSA level or an abnormal digital rectal examination. The most common abnormal laboratory findings in patients with metastatic prostate cancer are an elevated serum PSA level (typically > 10 ng/mL), an elevated serum alkaline phosphatase level, and anemia, which are all proportional to the extent of bone involvement.

Screening is still controversial

There has been considerable controversy in recent years with regard to PSA screening because of the lack of significant benefit and the potential for harm to the patient, with an overdiagnosis rate ranging from 23% to 42%.25

According to the ACS,26 certain groups of men should make an informed decision with their physician about whether to undergo screening: men over age 50 at average risk of prostate cancer and with at least a 10-year life expectancy, men over age 45 at high risk, and men over age 40 at an even higher risk. These ACS guidelines are consistent with those of the NCCN12 but differ from those of the USPSTF27 (Table 4).12,26,27

The patient should fully understand the risks and benefits of prostate cancer screening, as well as why it is controversial: ie, while the lifetime risk of being diagnosed with prostate cancer has increased, the lifetime risk of dying from it has remained the same after the advent of PSA testing.

Adverse effects of biopsy and treatment

Prostate biopsy is associated with infectious and bleeding complications, in addition to anxiety and physical discomfort.28 Treatment-related adverse effects include urinary incontinence, sexual dysfunction, and bowel problems.

Could these potential harms be overstated and the benefit be greater than currently thought? The NCCN12 noted that some of the landmark prostate cancer screening studies found a potential benefit in screening high-risk patients such as black men. Moreover, the studies used the sextant prostate biopsy technique, whereas now the extended core biopsy technique is the standard of care. And the studies may have underestimated the benefit of screening because the trial patients were relatively old (age 60) when their first PSA measurement was done, they were screened at long intervals (every 4 years), and the treatment options available at the time were not as good as those available today.12

Pearls

  • Laboratory findings in metastatic prostate cancer are proportional to the extent of bone involvement.
  • Most men with early-stage prostate cancer have no symptoms attributable to the disease.

Next Article:

Multiple linear subcutaneous nodules

Related Articles