Hypercalcemia can manifest as nausea, vomiting, abdominal pain, constipation, increased thirst, frequent urination, and altered mental status.

[15] Besides lung cancer many other diseases can also give this appearance, including hamartomas, and infectious granulomas caused by tuberculosis, histoplasmosis, or coccidioidomycosis.

[19] Their cells appear small with ill-defined boundaries, not much cytoplasm, many mitochondria, and have distinctive nuclei with granular-looking chromatin and no visible nucleoli.

Adenocarcinomas are classified as lepidic (growing along the surface of intact alveolar walls),[22] acinar and papillary, or micropapillary and solid pattern.

Around a third of people are diagnosed at the limited stage, meaning cancer is confined to one side of the chest, within the scope of a single radiotherapy field.

[28] The size and extent of the tumor (T), spread to regional lymph nodes (N), and distant metastases (M) are scored individually, and combined to form stage groups.

T3 tumors are up to 7 cm across, have multiple nodules in the same lobe of the lung, or invade the chest wall, diaphragm (or the nerve that controls it), or area around the heart.

[34] The United States Preventive Services Task Force recommends yearly screening using low-dose CT in people between 55 and 80 who have a smoking history of at least 30 pack-years.

[39] For chemotherapy, the National Comprehensive Cancer Network and American College of Chest Physicians guidelines recommend four to six cycles of a platinum-based chemotherapeutic – cisplatin or carboplatin – combined with either etoposide or irinotecan.

Combining standard chemotherapy with an immune checkpoint inhibitor can improve survival for a minority of those affected, extending the average person's lifespan by around 2 months.

In those with stage II disease, chemotherapy is usually initiated six to twelve weeks after surgery, with up to four cycles of cisplatin – or carboplatin in those with kidney problems, neuropathy, or hearing impairment – combined with vinorelbine, pemetrexed, gemcitabine, or docetaxel.

[51] In around 20 to 30% of those with lung cancer – particularly those with late-stage disease – growth of the tumor can narrow or block the airway, causing coughing and difficulty breathing.

In such cases the American College of Chest Physicians recommends opening the airway by inserting a stent, attempting to shrink the tumor with localized radiation (brachytherapy), or physically removing the blocking tissue by bronchoscopy, sometimes aided by thermal or laser ablation.

Some experience terminal delirium – confused behavior, unexplained movements, or a reversal of the sleep-wake cycle – which can be managed by antipsychotic drugs, low-dose sedatives, and investigating other causes of discomfort such as low blood sugar, constipation, and sepsis.

[66] The International Agency for Research on Cancer identifies at least 50 chemicals in tobacco smoke as carcinogenic, and the most potent is tobacco-specific nitrosamines.

[71] Similarly, exposure to radon, a naturally occurring breakdown product of the Earth's radioactive elements, is associated with increased lung cancer risk.

[72] Underground miners have the greatest exposure; however even the lower levels of radon that seep into residential spaces can increase occupants' risk of lung cancer.

[71] Exposure to air pollution, especially particulate matter released by motor vehicle exhaust and fossil fuel-burning power plants, increases the risk of lung cancer.

[73][74] Indoor air pollution from burning wood, charcoal, or crop residue for cooking and heating has also been linked to an increased risk of developing lung cancer.

[79] Many of these genes participate in pathways known to be involved in carcinogenesis, namely DNA repair, inflammation, the cell division cycle, cellular stress responses, and chromatin remodeling.

[80] As with all cancers, lung cancer is triggered by mutations that allow tumor cells to endlessly multiply, stimulate blood vessel growth, avoid apoptosis (programmed cell death), generate pro-growth signalling molecules, ignore anti-growth signalling molecules, and eventually spread into surrounding tissue or metastasize throughout the body.

Many such policies are mandated or recommended by the WHO Framework Convention on Tobacco Control, ratified by 182 countries, representing over 90% of the world's population.

[91] Consumption of polyunsaturated fats, tea, alcoholic beverages, and coffee are all associated with reduced risk of developing lung cancer.

[1] The ratio of lung cancer cases in men to women varies considerably by geography, from as high as nearly 12:1 in Belarus, to 1:1 in Brazil, likely due to differences in smoking patterns.

[103] A 1953 study showing that tar from cigarette smoke could cause tumors in mice attracted attention in the popular press, with features in Life and Time magazines.

Facing public concern and falling stock prices, the CEOs of six of the largest American tobacco companies gathered in December 1953.

[107] The committee's report, published in January 1964, firmly concluded that cigarette smoking "far outweighs all other factors" in causing lung cancer.

[108] The report received substantial coverage in the popular press, and is widely seen as a turning point for public recognition that tobacco smoking causes lung cancer.

As early as 1500, miners were noted to develop a deadly disease called "mountain sickness" ("Bergkrankheit"), identified as lung cancer by the late 19th century.

[113] Over the following decades, surgical development focused on sparing as much healthy lung tissue as possible, with the lobectomy surpassing the pneumectomy in frequency by the 1960s, and the wedge resection appearing in the early 1970s.