Lung cancer

Question 1

Small Cell Lung cancer (SCLC)

Answer 1

Hyponatremia:

• Frequently associated with hyponatremia. Usually asymptomatic.
• Can be precipitated by chemotherapy.
• Caused by release of ADH during lysis of tumor cells.
• Treatment includes hypertonic saline. Flutrocortisone can be used to correct hyponatremia.

Question 2

Treatment

Answer 2

Radiotherapy

Complications:

• radiation pneumonitis: inflammation of the lung caused by radiation therapy to the chest. Higher risk with prior induction or concurrent chemotherapy. Other risk fx inc smoking, COPD, ILD. Causes localised release of free-radicals, leukocytic infiltration, pulmonary oedema and exudative alveolitis. Incidence 7% (higher risk with large doses, large area, concurrent chemotherapy). Most commonly develops after 1 - 3 months, but can develop 6mo post treatment. Presents w dry cough, dyspnoea, low grade fever, inspiratory crepitations, pleural friction rub, pleural effusions, pleuritic chest pain. CXR may show perivascular haziness, patchy alveolar densities, or more dense opacities with time, small pleural effusions. Treated with corticosteroids (pred 20-40mg daily, taper over >6wks). Rarely fatal.
• Source: https://www.eviq.org.au/clinical-resources/radiation-oncology/side-effect-and-toxicity-management/1895-radiation-pneumonitis*

PJP prophylaxis:

• PJP (Pneumocystis jiroveci) causes pneumonia in patients with immunosuppression due to underlying malignancy, organ transplantation, bone marrow transplant, or other conditions, esp with concurrent use of corticosteroids.
• Cranial irradiation increases the risk of PJP (6.2% incidence over 12months, median time of set is 10wks)
• prophylaxis: Bactrim (Trimethoprim/sulfamethoxazole) is 1st line prophylaxis in adults and children. Dapsone is 2nd line (if TMP-SMX contraindicated), but need to rule out G6PD deficiency before.

Question 3

Lymphangitis carcinomatosis

Answer 3

Pulmonary tumor embolism and lymphangitic carcinomatosis are considered end-stage manifestations of malignancy.

Pulmonary tumor embolism refers to the identification of tumor within pulmonary blood vessels on pathologic lung samples. Invasion of the surrounding interstitium is not typically seen, a feature that distinguishes it from pulmonary metastases. Due to the prominent involvement of pulmonary vasculature, patients with this syndrome are more likely to present with the signs and symptoms of pulmonary hypertension and acute right heart failure.

Lymphangitic carcinomatosis is morphologically defined by the presence of tumor within pulmonary lymphatics. Tumor cells within pulmonary veins are not typically seen; however, tumor cells can invade the interstitium resulting in thickened bronchovascular bundles and interstitial septae. Since pulmonary capillary obstruction is not a feature of this disorder, patients with this syndrome are less likely to present with the signs and symptoms of pulmonary hypertension and acute right heart failure.

The diagnosis is most often post mortem.

Malignancies most often associated inc: RCC, HCC, breast, gastric, lung, CRC. Also seen with prostate, pancreatic, choriocarcinoma.

Pathophys: Tumor cells likely gain access to the lung via venous and lymphatic circulations (by direct invasion of nearby vessels) or possibly via transdiaphragmatic passage (eg, peritoneal carcinomatosis).