Lung Cancer

Lung cancer is the most common cause of cancer-related deaths among both men and women in the USA. It is predominantly a disease of the elderly: incidence increases with age, reaching 482/100,000 men > 65 years, and peaks at age 75, reaching about 502/100,000 men. A man aged 65 has a 50 times greater risk of developing lung cancer than a man aged 25, and a 3 to 4 times greater risk than men aged 45 to 64.

Etiology and Pathology

About 90% of lung cancer cases in men and 80% in women are attributable to cigarette smoking. The risk of lung cancer is related to the total years of smoking, which exposes smokers to carcinogens and promoting agents. Risk also increases in the elderly because of the age-related decline in cellular DNA repair. From initial exposure to cigarette smoke to clinical presentation, lung cancer probably has a 15- to 20-year natural history.

The four major histologic patterns of lung cancer are squamous cell carcinoma, adenocarcinoma, large cell carcinoma, and small cell carcinoma. Often, two or more of these patterns occur simultaneously.

Squamous cell carcinoma is the most common lung cancer among the elderly, accounting for 40 to 50% of lung cancers among patients > 65. These tumors often grow slowly and usually arise in central airways.

Adenocarcinoma is the second most common lung cancer, accounting for 30 to 35% of lung cancers among the elderly. These tumors probably arise from bronchial and mucosal glands. Except for stage I lesions (see Table 81-1), adenocarcinoma generally has a worse prognosis than squamous cell carcinoma.

Large cell carcinoma accounts for 15% of all lung cancers. Usually, it is distinguished by the absence of the distinctive characteristics of the other types. Newer staining techniques allow some tumors once classified as large cell to be reclassified as poorly differentiated squamous cell carcinoma or adenocarcinoma. The site of origin of large cell carcinoma is similar to that of adenocarcinoma.

Small cell (oat cell) carcinoma accounts for 15 to 20% of all lung cancers and is somewhat more common in patients > 65, accounting for slightly more than 25% of all lung cancers in this population. Small cell tumors invade the submucosa early in their growth, and patients usually present with regional or distant metastases at diagnosis. Small cell carcinoma is the most rapidly growing and most chemoresponsive of all lung cancers.

Symptoms, Signs, and Diagnosis

The symptoms and signs that commonly accompany local and regional lung cancer are listed in Table 81-2. Patients >= 50 who are current or former smokers and who present with community-acquired pneumonia should raise particular concern. The routine practice of waiting up to 3 months for community-acquired pneumonia in an elderly smoker to clear may delay early detection of lung cancer. An elderly current or former smoker with a cough and an infiltrate without fever and purulent sputum should be assumed to have lung cancer until tests prove otherwise.

Cytologic screening may be useful in detecting squamous cell carcinoma in elderly cigarette smokers. Overall, however, routine cytologic screening fails to detect lung cancer cells at a stage early enough to perform surgical resection or to lengthen survival.

Chest x-ray is usually the initial diagnostic tool, although it is not useful as a screening tool. CT scans are a valuable addition to chest x-rays for determining mediastinal tumor extension. However, CT scans yielded false-negative results in 5 to 9% of cases, in which they indicated only local involvement.

Mediastinoscopy is often used to stage lung cancer and as a prelude to surgical resection of the involved lung to confirm the clinical staging.

Prevention and Treatment

Smoking cessation reduces the risk of lung cancer mortality at any age, and the earlier a smoker quits, the better. The approach to smoking cessation is no different for the elderly than it is for younger patients.

In the elderly, lung cancer usually manifests at a less advanced stage, and treatment, therefore, is usually more successful. However, the diagnostic and therapeutic options offered to the elderly are often substantially less aggressive. Treatment decisions should be based not on age, but rather on cancer type and stage, functional status (see Tables 81-3 and 81-4), organ function, pulmonary function, cardiopulmonary test results, and comorbidities. For some elderly patients with severe disease, such as advanced dementia or renal, cardiac, or pulmonary disease, treatment may be best aimed at relieving symptoms rather than at attempting cure.

Treatment for non-small cell lung cancer depends on tumor stage, as categorized by the international TNM staging system (see Table 81-1). Small cell lung cancer is usually metastatic; thus, treatment is based on whether cancer is limited or extensive rather than on whether it is localized or metastatic.

Surgery: Age alone is not a contraindication to potentially curative surgery. For patients with adequate pulmonary reserve and no evidence of extrathoracic (bone, brain, or liver) metastases, the extent of mediastinal and thoracic lymph node involvement determines whether curative resection is possible. Tissue (surgical) staging must be performed in patients who are otherwise acceptable candidates for surgical resection but who have enlarged mediastinal lymph nodes. Staging is sometimes accomplished through mediastinoscopic or needle transtracheal lymph node sampling. If the tumor is found to extend to the mediastinum, the disease is considered incurable and surgery is not beneficial. Surgery is not recommended for most patients with advanced (stage IIIB, stage IV) non-small cell lung cancer.

Curative surgical treatment for non-small cell lung cancer may be considered for patients with stage I or II disease. However, only 20 to 25% of all patients with lung cancer meet the criteria even before clinical staging is completed. The success of lung cancer resection, the choice of adjuvant therapy, and prognosis for resected non-small cell lung cancer depend on the extent of metastases.

A predicted postoperative forced expiratory volume in 1 second (FEV₁) of > 800 mL is usually considered a minimum for consideration of surgery, because hypercapnia often occurs below this level. Hypoxia (partial pressure of arterial O₂ [Pao₂] < 50 mm Hg) and hypercapnia (partial pressure of arterial CO₂ [Paco₂] > 45 mm Hg) are also risk factors for increased perioperative mortality.

Perioperative pulmonary complications in the elderly can be minimized by preoperative smoking cessation, intensive pulmonary physical therapy, antibiotic therapy (for existing bronchitis), bronchodilator therapy, and postoperative pulmonary rehabilitation. Perioperative complications correlate with preoperative physiologic measurements (eg, FEV₁, maximum minute ventilation, maximal oxygen consumption).

Postoperative mortality is 1.3% for patients < 60, 4.1% for patients 60 to 69, and 7.1% for patients >= 70. Mortality is at least partially dependent on the operation performed. Expected postoperative mortality rates for lung cancer surgery are 11.6% for pneumonectomy, 4.2% for lobectomy, and 3.7% for segmentectomy. Pneumonectomy is associated with a two to seven times greater risk of mortality for the elderly than for patients < 65. Respiratory complications occur twice as often in patients >= 75. Elderly cigarette smokers, who are most likely to develop lung cancer, commonly have coronary artery disease and ventilatory obstruction as well, thus increasing the risk of surgery. When patients also have chronic obstructive pulmonary disease and emphysema (frequently due to cigarette smoking), the risk of postoperative pneumonia and atelectasis increases.

Chemotherapy: Cure with chemotherapy is rare. Length of survival may be improved with chemotherapy, but quality of life may be compromised by significant adverse effects of treatment. How well chemotherapy is tolerated depends more on functional status than on age (see Tables 81-3 and 81-4), even in patients with extensive disease. Thus elderly patients must weigh the same considerations as must younger patients. Response rates to treatment for advanced lung cancer are similar across age groups. In the case of advanced-stage small cell lung cancer, the response rate approaches 80% and the 2-year survival rate is up to 10%, so that chemotherapy is often appropriate.

Radiation therapy: Radiation can be used as primary therapy or for palliation and pain control in advanced disease. Local control of unresectable disease often can be achieved with radiation therapy, although control of metastases and cure are uncommon. Patients with locally (T3, T4) or regionally (N2, N3) advanced non-small cell cancer often receive radiation therapy alone or combined with chemotherapy as primary treatment. Patients with distant metastases (M1) receive radiation therapy for palliation and pain control. When staging studies confirm that small cell cancer is limited, reported median survival is 10 to 16 months with radiation therapy. However, radiation may not prolong survival.

In general, elderly patients tolerate palliative radiation therapy as well as younger patients. However, radiation pneumonitis is more clinically severe among the elderly. Newer radiation modalities and computer-assisted or computer-directed treatment may lessen the severity of pneumonitis.

Nursing and Caregiver Issues

Nursing care must be tailored to the patient's prognosis as determined by the type and stage of cancer as well as any comorbidities. For patients who require surgical intervention, pain management and pulmonary function are likely to be key nursing issues. Early in the postoperative period, pain is usually acute at the incisional site and later tapers off. The use of drugs for pain management must be appropriate to the degree and extent of pain expressed by the patient. Deep-breathing and coughing exercises help maintain adequate ventilation in the postoperative phase. For patients receiving radiation therapy or chemotherapy, any adverse effects must be assessed and treated appropriately. For patients who have previously smoked or have been exposed to lung irritants, chest physical therapy and regular auscultation to detect early symptoms and signs of adverse events such as pneumonia, atelectasis, and pneumothorax are essential.

For patients whose disease has been newly diagnosed, support groups and patient education may be helpful. Family and friends should be included to the greatest degree possible to ensure adequate support and educational impact.

End-of-Life Issues

Although lung cancer may be curable if detected early, most cases are ultimately fatal. The realistic chances that treatment will prolong life or improve the quality of life must be discussed with the patient. The patient should also be informed of the likely adverse effects of treatment. The patient's wishes regarding terminal care should be discussed and documented early.

In the late stages of lung cancer, patients are likely to experience pain, shortness of breath, anorexia, and weight loss and may become depressed. Such symptoms should be fully treated. In the terminal stages, full doses of opioids may be needed for patients distressed by hypoxia.