LUNG CANCER AND STAGES

What is lung cancer?

Cancer is the uncontrolled growth of cells within the body. Usually, all of our cells have a specific lifespan of days to years that is genetically programmed in our DNA. When our DNA becomes damaged, either through the aging process, exposure to toxins such as radiation or chemicals or through inherited genes, some cells do not die a natural death but continue to grow. As they do, they form new cells with the same genetic misinformation. These extra cells may form masses or tumours that can be either malignant or benign. A benign tumour is a tumour that does not invade the surrounding tissue or spread around the body and stays in one place. A malignant tumour can invade the surrounding tissue or spread via the blood or lymph networks and affects other cells and organs.

Approximately 6.5% or one in fifteen of the global population will develop some form of lung cancer during their lifetime. It is the most common cancer in the world, either as a primary site of cancer cell growth or as a destination for cancer cells produced in other parts of the body where it is known as metastatic lung cancer.

Most cases of lung cancer are first diagnosed after the development of a cough that simply does not go away, hoarseness, the appearance of blood in the sputum or unexplained weight loss or shortness of breath. Very early diagnosis usually happens during chest X-rays for other respiratory disorders such as pneumonia or the presence of cancerous cells in sputum samples. Other cases of early detection are found in those populations who suffer from chronic lung disorders such as COPD or cystic fibrosis. These groups usually visit their pulmonologist at regular intervals and are aware of the signs of lung cancer.

Screening programs for lung cancer are uncommon and it is usually up to the patient to ask. As the only recommended screening test is via a CT scan which emits low doses of radioactivity, these tests are only carried out on people with a history of heavy smoking who either continue to smoke or have given up in the past 15 years and are over 55 years of age. These criteria mean that many non-smokers are left out of the loop and with increasing numbers of patients having never smoked, current screening programs are insufficient. As regular CT scans can be damaging to your overall health, being aware of the early signs is important.

Women have a very slightly lower risk of developing lung cancer when compared to men, although these numbers are gradually rising. One in five women who develop lung cancer has never smoked, and this is true of one in every ten men. And it is not only second-hand smoke that increases risk for non-smokers – indoor coal fires for cooking and heating and some cooking fuels are known carcinogens. Another known risk factor is living in or working in environments with medium to high levels of pollution. And the presence of other cancer types in the body that form secondary tumours in the lungs also increase one’s chances of developing lung cancer.

Treatments for lung cancer prevent further growth, most commonly via chemotherapy, and often involve surgery.

 Are there different types of lung cancer?

There are various forms of lung cancer and your medical notes may be difficult to understand. Most specific lung cancer types are based upon the features of their abnormal cells. 

Primary lung cancer which starts in the lungs and is not secondary to other cancers are divided into two main groups known as small cell lung cancer (SCLC) and non small cell lung cancer (NSCLC). The latter of these is the most common group and consists of smaller groups: adenocarcinomas (ADC), squamous cell carcinomas (SCC), large cell carcinomas (LCC), large cell neuroendocrine carcinomas (LCNEC) and giant cell carcinomas. Small cell lung cancer is less common and usually the result of regular contact with cigarette smoke. Finally, combined small cell carcinoma (c-SCLC) is a tumour containing both small cell and non small cell components. All of these cancer cell types will be looked at in more detail below.

If you have cancer of the lung due to the metastasis of another cancer such as colon cancer, prostate cancer or breast cancer, your cancer will be named according to the primary source. Secondary lung cancer is not the result of mutations in lung cells but due to bowel, breast, prostate or any other type of cancer cell reaching the lungs and growing there. These cells do not become lung cells. This is why metastatic lung cancer is not dealt with in detail in this article.

Small cell lung cancer

Small cell lung cancers – previously referred to as oat cell cancers - are rarer than non small cell types but more aggressive and can grow quickly. They are also likely to metastasise to other areas of the body such as the liver, brain and bone if not caught in time. Most cases of SCLC are the result of smoking cigarettes or breathing in significant quantities of cigarette smoke produced by others, such as when living with a heavy smoker or working in an environment where smoking takes place. 

This type of cancer usually starts in the centre of the chest at the bronchi and is difficult to treat.

Combined small cell lung cancer

Where other cancer cells that are different to small cells are present in a cancerous lesion of the lung, your diagnostic notes may feature the acronym c-SCLC. This type of cancer – combined small cell lung cancer - is often treated in the same way as small cell lung cancer but contains non small cell lung cancer types that may respond better to other therapies. It is therefore important that you have access to an experienced oncologist specialised in lung carcinomas. Remedazo works with a number of highly specialised oncological consultants.

Most of those with the combined cancer type are around 60 years of age and male and have a history of heavy smoking, just like those groups diagnosed with small cell lung cancer. However, this cancer type is also found in younger and older men and women with no history of smoking. The most frequent clinical symptoms of c-SCLC are coughing, trouble breathing and coughing up small or large quantities of blood. Tumours can start to grow anywhere in the lung and are more likely to be found further from the bronchi than small cell lung cancers.

Furthermore, c-SCLC tends to be detected at earlier stages than SCLC and does not metastasize as rapidly. It may respond better to surgery and radiotherapy but not as well to chemotherapy. Finally, very specific mutations in special cells known as epidermal growth factor receptors (EGFR) are not often found in small cell lung cancer types but prolific in non small cell lung cancer. This is important, as these mutations are not only treated differently but can also provide a means for blood sample detection at a much earlier stage.

Non small cell lung cancer

Non small cell lung cancer is the most common form of lung cancer in those who have never smoked. Non small cell lung carcinomas (the terms carcinoma and cancer are interchangeable) tend not to respond to chemotherapy as well as small cell lung cancers and the first line of treatment is therefore surgical. Surgical removal of a non small cell tumour without metastasis can be a curative therapy. Even though these cells are less sensitive to chemotherapy it is still given either before surgery to shrink the tumour (neoadjuvant therapy) or after surgery to kill off remaining cells (adjuvant therapy).

Adenocarcinoma (ADC)

The most common type of NSCLC, lung adenocarcinomas are often found on the outer surfaces of the lung and involve secretory cells such as those that produce mucus. Unlike most types of lung cancer, adenocarcinomas of the lung are more often found in women, many of whom are non-smokers. Because they grow slowly they are often detected at a later stage; any symptoms they produce are typical to lung cancer such as a cough that does not go away, blood in the sputum and unexplained weight loss. 

Squamous cell carcinoma (SCC)

Squamous cell lung cancer begins in the thin, flat squamous cells of the airway lining, usually close to the central portion of the lung or a major airway. This type of non small cell cancer is more likely to be found in smokers or in those exposed to high levels of second hand smoke, certain chemicals such as asbestos and gases such as radon in the home or working environment. Symptoms at later stages are comparable to all types of lung cancer.

Large cell carcinoma (LCC)

Large cell carcinoma used to be confused with adenocarcinoma but better techniques now make it possible to distinguish cell types with more accuracy. This means that previous estimates of 10% of all lung cancers being due to LCC have now dropped to just 2%. Most people with LCC are men aged between 50 and 70 years of age who have smoked or still smoke. Treatment usually requires surgery as well as courses of chemotherapy and radiation

Large cell neuroendocrine carcinoma (LCNEC)

This type of lung cancer is very rare. Usually found on the outer regions of the lungs, this cancer type is most often found in older men who smoke. This can be an aggressive cancer that often returns after treatment and is sometimes found together with other non small cell cancer cell types. Early stage treatments are surgery and chemotherapy. Later stage treatments primarily use chemotherapy, targeted therapy and immunotherapy to slow tumour growth.

Giant cell carcinoma

Giant cell carcinoma of the lung (GCCL), sometimes referred to as sarcomatoid carcinoma, is distinguishable by its large cells and rarely co-exists with other cancer cell types. It is extremely rare and most commonly found in middle aged to older men who are heavy smokers. In order to be diagnosed, surgical biopsy is required. Treatment is usually surgical in combination with radiation treatment, although this type of lung cancer is often detected after it has metastasized and is very aggressive. It does not respond well to chemotherapy. Recent studies show that targeted therapy can significantly lengthen survival in those who have certain growth factor mutations (EGFR mutations).

Lung cancer stages

Your medical notes may have listed a number of codes concerning your lung cancer diagnosis. Or perhaps you are waiting for further testing and prefer to be well-informed before receiving your results.

In the case of small cell lung cancer, there are only two clinically-defined stages. These are ‘limited’, where cancer is found in one lung and/or one or more regional lymph nodes on the same side of the chest and ‘extensive’, where cancer has spread throughout one lung, to the opposite lung, to the lymph nodes on the opposite side of the chest, to the pleura and pleura fluid, to the bone marrow or to the distant organs (metastasis). Because of its rapid growth, around 60% of people with SCLC are diagnosed in the extensive stage. Combined small cell lung cancer is usually slower growing and more likely to be detected in the limited stage than SCLC.

Non small cell lung cancers are staged using the universal TNM staging system according to tissue samples (biopsy) and imaging results.

T stands for tumour. T plus a letter or number describes the size (in centimetres) and location of a tumour. Where more than one tumour is present, the letter ‘m’ (multiple) is added. T letter and number systems for lung tumours are:

• TX: It is not possible to evaluate the tumour due to a lack of data

• T0: No evidence of a primary tumour

• Tis: The carcinoma is restricted to a small area

• T1: The tumour is local to the lung but not the bronchus and 3 cm or smaller

  • T1a(mi): A minimally invasive carcinoma

  • T1a: The tumour is local to the lung and 1 cm or smaller

  • T1b: The tumour is local to the lung and between 1 cm and 2 cm

  • T1c: The tumour is local to the lung and between 2 cm and 3 cm

• T2: The tumour is local to the lung and larger than 3 cm

  • T2a: The tumour is local to the lung and between 3 cm and 4 cm

  • T2b: The tumour is local to the lung and between 4 cm and 5 cm 

• T3: The tumour has grown into the outer lining of the chest wall, pericardium or phrenic nerve but is not outside of these areas. The tumour is between 5 cm and 7 cm.

• T4: The tumour has spread to areas beyond the chest wall (into the mediastinum, diaphragm, heart, large blood vessels, trachea or oesophagus) or a second tumour has been found in another lobe of the same lung or in the opposite lung. The primary tumour is greater than 7 cm.

N stands for nodes or lymph nodes and the following codes apply:

• NX: Regional (nearby) lymph nodes cannot be evaluated due to lack of data

• N0: No spread to regional lymph nodes

• N1: Tumour has spread to regional lymph nodes

• N2: Cancerous cells in lymph nodes of the mediastinum or trachea

• N3: Cancerous cells in the lymph nodes on the opposite side of the chest to the primary tumour

Finally, M stands for metastasis. The following codes apply:

• M0: There is no spread to distant lymph nodes or other organs

• M1: Distant metastasis is present in distant lymph nodes and/or to other organs. 

  • M1a: Cancer has spread to the other lung

  • M1b: Cancer has spread to 1 distant site

  • M1c: Cancer has spread into one or more other organs

Lung cancer metastasis (M1b to M1c) is most likely to affect the liver, bone marrow and/or brain.

Your medical notes may also contain reference to NSCLC stage I, 2, 3 or 4. These stages are based upon your TNM scores.

Stage 1 NSCLC is a curable lung cancer requiring surgery to remove the affected part of the lung. Chemotherapy is sometimes recommended for those in whom recurrence is possible. Stage two usually requires surgery and almost always chemotherapy. Stage 3 commonly requires at least three therapies – surgery, chemotherapy and radiation treatment. Finally, stage 4 NSCLC will include targeted and immunotherapies, as well as chemotherapy, perhaps with radiation treatment and surgery.