Malignant Tumors of the Lung

Incidence of lung cancer in the United States has been declining among men and only recently began decreasing in women.

Overall prevalence is approximately 125 per 100,000 people per year.

Estimated new cases per year in the United States: 212,584 (111,907 male and 100,677 female)

Primary lung malignancies are the leading cause of cancer deaths, accounting for 13% of all new cancers and 26.5% of all cancer deaths.

Estimated deaths per year in the United States: 158,080

Remains by far the leading cause of cancer-related deaths in both sexes in the United States

Overall 5-year survival rate is 17.8%; for localized disease this increases to 54%.

Overall risk for lung cancer in smokers versus nonsmokers is 20–25 times greater.

Only 10% of patients with lung cancer are nonsmokers, but 25%–50% of these patients have significant second hand smoke exposure.

The current downtrend in national incidence of smoking reflects the decline in the incidence of lung cancer diagnosis.

Importantly, the increasing incidence of lung cancer in never-smokers, particularly women, is a serious public health issue.

Radon

Asbestos (more common cause of lung cancer than mesothelioma)

Ionizing radiation

Arsenic

Nickel

Chromium

Mustard gas

Chloromethyl ethers

No proper screening method was available until results of the National Lung Screening Trial (NLST) were published in 2011.

Lung cancer has a high morbidity and mortality, significant prevalence, identifiable risk factors, and evidence that therapy is more effective in early stages.

NLST demonstrated at least 20% reduction in lung cancer–specific death in high-risk patients (i.e., >55 years of age with >30 pack-years of smoking).

Chest x-ray (CXR) and/or sputum culture—no longer recommended. No impact on mortality

Low-dose chest computed tomography (LDCT)—multidetector CT scanners use low-dose radiation (10 times less than diagnostic scans) to generate high-resolution imaging.

• a.

  Imperative to understand that this is a process rather than a test (i.e., patients have to commit to follow-up as needed to achieve reduced mortality)

• b.

  NLST—LDCT in high-risk patients yearly for at least 3 years

  • (1)

    Participants aged 55–74 years with a history of at least 30 pack-years, including current smokers and those who had quit within 15 years

  • (2)

    Demonstrated that LDCT screening reduced mortality in high-risk population compared with CXR screening—at least 20% reduction in mortality (trial was stopped early given substantial results).

  • (3)

    A total of 96.4% of scans were positive, making a multidisciplinary approach an essential component of the process to minimize unwarranted interventions.

• c.

  Societies recommending the implementation of the NLST guidelines

  • (1)

    American Association for Thoracic Surgery (AATS)—recommend LDCT screening in high-risk patients between ages 55 and 79 years.

  • (2)

    National Comprehensive Cancer Network (NCCN)—annual LDCT screening for high-risk patients aged 55–74 years or age ≥50 with a history of 20 pack-years with additional risk factor (other than second hand smoke exposure)

• d.

  Centers for Medicare and Medicaid Services (CMS) started covering LDCT screening of lung cancer in 2015.

Positron emission tomography (PET) scans—not a recommended screening modality

• a.

  Sensitivity 96%, specificity 79%

• b.

  False negative—tumors with low metabolic activity such as carcinoma in situ, carcinoid tumors, tumors with sizes below the resolution (typically <10 mm), and patients with uncontrolled hyperglycemia

• c.

  False positive—inflammation or infection, typically with standardized uptake value (SUV) less than 2.5

• d.

  LDCT followed by PET scan in patients with noncalcified lesions ≥7 mm had sensitivity of 61% and specificity of 91%, with a negative predictive value (NPV) of 71%. If then followed by a repeat CT, NPV increased to 100%.

A solitary pulmonary nodule (SPN) is defined as ≤3 cm surrounded by normal lung parenchyma and without adenopathy, atelectasis, or pleural effusion.

A lesion greater than 3 cm is defined as a mass.

Patients with an SPN undergo evaluation based on the suspicion for malignancy, whereas those with a mass undergo work-up for suspected malignancy.

Lung malignancy, primary or metastatic

Inflammation—sarcoidosis

Infection—granulomas, fungal balls

Congenital lesion—hamartoma

Vascular—pulmonary vascular arteriovenous malformations (PVMs)

Previous trauma

Small (<3 cm), smooth with sharply circumscribed margins

Benign calcification—laminar, central, diffuse/homogeneous, and popcorn patterns

Stable in size on CT imaging over 2-year period (solid), 3 years for a subsolid nodule—doubling time is 20–400 days for malignant tumors.

Depends greatly on size of the lesion and if the lesion has increased in size, patient’s age, and smoking history, as well as additional characteristics on CT scan (calcifications, spiculations)