There are 4 basic types of lung cancer. Which one is the most difficult to treat?

Lung cancer is the type of cancer with the highest morbidity and mortality in the world. Lung cancer is mainly divided into non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), with non-small cell lung cancer accounting for about 85% of lung cancer. The proliferation and expansion of small cell lung cancer and non-small cell lung cancer are completely different, and the treatment measures are also different.

There are 4 basic types of lung cancer. Which one is the most difficult to treat?

Microscopic non-small cell lung cancer (NSCLC) includes adenocarcinoma, squamous cell carcinoma and large cell carcinoma. They are classified as one type mainly because their growth patterns are similar and their treatment measures are similar. The cell morphology of these three types of non-small cell lung cancer under the microscope is obviously different, so for patients with a change in classification, it is still easy to detect it by re-taking tissue samples for testing.

Three types of non-small cell lung cancer under the microscope The characteristics and treatment measures corresponding to different subtypes of lung cancer are also different. The following editor will give you a more detailed summary:

Lung cancer classification and corresponding characteristics:

1. Non-small cell lung cancer (NSCLC)

1. Characteristics of lung adenocarcinoma:

Adenocarcinoma accounts for 40% of all lung cancers and about 55% of non-small cell lung cancers. This proportion is higher in non-smoking Asian patients.

Adenocarcinoma includes many subtypes such as alveolar adenocarcinoma, papillary adenocarcinoma, bronchioloalveolar carcinoma (BAC), solid adenocarcinoma and various mixed types. Among them, bronchioloalveolar carcinoma originates from the alveoli and often grows slowly. Compared with NSCLC, it is less likely to metastasize. BAC is often considered a subtype with a better prognosis.

The tumors often take up space in the peripheral areas of the lungs.

The more common mutated genes are EGFR, ALK, cMET, ROS1, HER2, KRAS, etc., which are also the cancers with the most targeted drugs. The probability of EGFR gene mutation in non-smoking female Asian patients is as high as 50%, and the drugs that can be used are gefitinib, erlotinib, and icotinib; the targeted drugs that can be used for ALK mutations are crizotinib, ceritinib, alectinib, etc.

2. Characteristics of squamous cell lung cancer:

The incidence of squamous cell carcinoma has decreased in the last 30 years, but it is a common subtype in smokers. It is more common in male patients and often originates in the larger airways, so it often occupies the center of the lung. Under the microscope, it is a large, flat cell. It often produces keratin, which can be seen under a microscope. Blood tests for keratin are also a monitoring indicator.

Squamous cell carcinoma sometimes metastasizes later than other NSCLC subtypes and often invades adjacent tissue structures.

It accounts for about 25% of the total number of lung cancers. Common gene mutations include FGFR1, STK11, SOX, PIK3CA, DDR2, PDGFRA, MDM2, etc. Targeted drugs for squamous cell carcinoma are in the clinical stage. The most recently approved ones are PD-1 immune point inhibitors, nivolumab and pembrolizumab, but they are expensive.

3. Characteristics of large cell carcinoma:

It accounts for about 10%-15% of non-small cell lung cancer. Large cell carcinoma includes several subtypes, such as clear cell large cell carcinoma, basaloid large cell carcinoma, pulmonary lymphoepithelioma-like carcinoma, and pulmonary large cell neuroendocrine carcinoma.

Under the microscope, they appear as highly undifferentiated or immature large cells.

It can occupy any part of the lung, with no tendency to be peripheral or central.

Compared with other subtypes of non-small cell lung cancer, the prognosis is often not particularly good.

There are currently no particularly effective targeted drugs for large cell lung cancer. There are literature reports that there are cases where EGFR mutations are effective for gefitinib. Testing for gene mutations and using drugs across indications can be considered.

2. Small Cell Lung Cancer

Characteristics of small cell lung cancer:

It accounts for about 15% of all lung cancers. It is highly malignant and has limited treatment options. There are currently no approved targeted drugs and it initially responds well to chemotherapy and radiotherapy.

The occurrence of small cell lung cancer is closely related to smoking, and only 1% of small cell lung cancer is not related to smoking.

It grows and spreads faster than non-small cell lung cancer and tends to metastasize in the early stages of the disease. Most patients have already metastasized when they are diagnosed.

Small cell lung cancer is often located in the center of the lungs because it tends to occupy larger airways.

The stage of lung cancer is based on whether the tumor is localized or has metastasized to lymph nodes or other tissues and organs. Lung cancer takes more than ten years to develop, and even if some symptoms of lung cancer such as coughing and fatigue have already occurred, people often think that they are caused by other reasons. Therefore, early lung cancer (stage I and stage II) is difficult to detect.