Targeted cancer therapies (tyrosine kinase inhibitors and monoclonal antibodies)

Cancer treatment-related cardiotoxicity covers five distinct syndromes: irreversible, cumulative-dose-dependent anthracycline cardiomyopathy; typically reversible trastuzumab/HER2-targeted left ventricular dysfunction; radiation-induced coronary, pericardial, valvular, and conduction disease appearing years after chest irradiation; tyrosine kinase inhibitor and VEGF-inhibitor hypertension and QT prolongation; and immune checkpoint inhibitor myocarditis, a distinct fulminant entity requiring urgent high-dose corticosteroids and permanent drug discontinuation.

Immune checkpoint inhibitor toxicity is the set of autoimmune-like immune-related adverse events (irAEs) that follow blockade of CTLA-4, PD-1, or PD-L1, most often colitis, hepatitis, pneumonitis, dermatitis, and endocrinopathy. Diagnosis relies on excluding infection and grading severity; first-line treatment for grade 2 or higher toxicity is oral or intravenous corticosteroids with the checkpoint inhibitor held or permanently stopped.

Chronic myeloid leukemia is a myeloproliferative neoplasm driven by the Philadelphia chromosome t(9;22), which produces the constitutively active BCR-ABL1 tyrosine kinase and marked, left-shifted granulocytosis with a low leukocyte alkaline phosphatase score. Diagnosis is confirmed by cytogenetics or molecular testing for BCR-ABL1, and a BCR-ABL tyrosine kinase inhibitor such as imatinib is first-line, continued indefinitely with molecular-response monitoring, reserving allogeneic transplant for TKI failure or blast crisis.

Breast cancer is a malignancy of ductal or lobular epithelium, most often presenting as a firm, painless mass in the upper outer quadrant. Diagnosis rests on core needle biopsy with estrogen, progesterone, and HER2 receptor testing, and first-line treatment pairs breast-conserving surgery or mastectomy with sentinel node biopsy, radiation, and receptor-guided systemic therapy such as tamoxifen or trastuzumab.

Lung cancer is the leading cause of cancer death worldwide, split into non-small cell lung cancer (NSCLC, 80% of cases: adenocarcinoma, squamous cell, large cell) and small cell lung cancer (SCLC, 10-15%), both driven overwhelmingly by cigarette smoking. Diagnosis requires tissue histopathology, staging drives treatment (TNM staging for NSCLC, limited versus extensive stage for SCLC), and management ranges from lobectomy in early-stage disease through concurrent chemoradiation and consolidation immunotherapy in locally advanced disease to targeted tyrosine kinase inhibitors, immune checkpoint inhibitors, or platinum-based chemotherapy in metastatic disease.

Colorectal cancer is an adenocarcinoma that arises through the adenoma-carcinoma sequence and presents differently by location, with right-sided tumors causing occult bleeding and iron-deficiency anemia and left-sided tumors causing obstruction and hematochezia. Colonoscopy with biopsy confirms the diagnosis, TNM staging on CT chest/abdomen/pelvis with CEA guides treatment, and management ranges from surgical resection alone for localized disease to adjuvant FOLFOX for node-positive colon cancer, neoadjuvant chemoradiation for rectal cancer, and molecularly targeted systemic therapy for metastatic disease.

Hepatitis B virus is a bloodborne and sexually transmitted DNA virus that causes acute hepatitis and, when infection becomes chronic, progresses through immune-tolerant, immune-active, immune-control, and reactivation phases toward cirrhosis and hepatocellular carcinoma. Diagnosis rests on hepatitis B serology, chronic infection is treated with entecavir or tenofovir, and reactivation during immunosuppression is prevented with prophylactic antiviral therapy.

Drug-induced interstitial lung disease is parenchymal lung injury caused by a medication, most often amiodarone, methotrexate, nitrofurantoin, bleomycin, busulfan, nitrosoureas, gemcitabine, or immune checkpoint inhibitors, with patterns ranging from acute pneumonitis and ARDS to organizing pneumonia, eosinophilic pneumonia, and fibrosis indistinguishable from idiopathic pulmonary fibrosis. It is a diagnosis of attribution: a temporal drug exposure, compatible imaging, exclusion of infection and other causes, and improvement after withdrawal. Stopping the drug is mandatory; glucocorticoids are added for hypoxemic disease, and checkpoint inhibitor pneumonitis is treated by grade.