What is Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer?
Lung cancer is the most common type of cancer in the world that isn’t related to skin cancer. The majority of cases are due to smoking. This type of cancer is a serious global health problem, with non-small cell lung carcinoma (NSCLC), a common type of lung cancer, making up most of the cases. Lung cancer can cause various symptoms, ranging from breathing problems to neurological issues. Correctly identifying and determining the stage of lung cancer are crucial steps in handling the disease. This process involves a mix of clinical assessments, imaging tests like X-rays, and tissue samples.
The management of NSCLC can be complex, but radiation therapy provides a viable alternative to surgery in cases where the patient is not healthy enough for a surgical procedure. Despite historical challenges with radiation therapy, recent advancements have boosted its appeal, with improved survival rates seen in lung cancer patients 3 years post-diagnosis. Techniques like stereotactic body radiotherapy (SBRT), a type of high-precision radiation therapy, are showing promising results, although further research is needed to validate these outcomes. The hope is to find a balance between effective treatment and minimizing potential side effects through the use of combined therapies and careful dosage planning, symbolizing an evolving approach in early NSCLC management.
What Causes Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer?
Using tobacco is the leading cause of lung cancer. It’s linked to 90% of lung cancer cases in men and 70% in women. But there are other things in the environment that can increase your risk as well. This includes being exposed to radon, a radioactive gas, asbestos which is a mineral used in insulation, and certain substances at work. These substances can include arsenic a poison, bis-chloromethyl ether used in chem labs, hexavalent chromium known to cause cancer in animals, mustard gas a chemical weapon, nickel a metal, and polycyclic aromatic hydrocarbon which is found in soot.
Risk Factors and Frequency for Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer
In the United States, lung cancer ranks as the second most frequent type of cancer. It comes after breast cancer in women and prostate cancer in men, if we don’t count skin cancer. Approximately 14% of all new cancer cases are lung cancer. Every year, around 220,000 new cases of lung cancer are detected, leading to an estimated 155,000 deaths. Lung cancer holds the unfortunate title of being the most common fatal cancer for both men and women. In fact, lung cancer causes more deaths than prostate, breast, and colon cancers combined. Over the past several decades, there has been a decrease in lung cancer cases among men and more recently, also among women.
Signs and Symptoms of Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer
Non-Small Cell Lung Cancer (NSCLC) is usually characterized by symptoms such as shortness of breath, coughing, coughing up blood, chest pain, and unexplained weight loss. Some people may also experience changes in their mental state, an unusual rounding of the fingernails and toenails (known as “clubbing”), lung infections due to obstructed airways, fluid build-up around the lungs (pleural effusion), hoarseness from damage to the laryngeal nerve, and a condition called superior vena cava syndrome.
Certain patients may have tumors located at the top of the lung, known as superior sulcus tumors. These can lead to a condition known as Pancoast syndrome. This syndrome is recognized by shoulder pain, nerve damage in the arm and hand, and a triad of conditions known as Horner syndrome. Horner syndrome involves drooping of the upper eyelid, a small pupil, and reduced sweating on the same side of the face.
Certain factors can indicate a worse prognosis, which means a more severe course and outlook of the disease. These factors include:
- An advanced stage of the tumor
- Loss of more than 10% of body weight over the past six months
- A Karnofsky Performance Status score of less than 90, which measures a patient’s physical abilities and quality of life
- The presence of pleural effusion
- Being above the age of 70
- Use of chemotherapy
- The stage of lymph node involvement in the disease
Testing for Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer
If your doctor suspects that you might have lung cancer, they will first check your health history and give you a physical examination. They will want to know how well you can handle everyday activities, if you have lost weight recently, and if you have a history of tobacco use. After that, they will conduct a series of tests including imaging tests and lab tests.
The imaging tests could include a CT scan of your chest, abdomen, and pelvic area. CT scans are essentially specialized x-ray tests that can produce detailed images of the inside of your body. They may also do a brain MRI, which uses powerful magnets and radio waves to create images of your brain. They might also order a PET-CT which is a combination of a PET scan and a CT scan. PET scans are typically used to detect cancer because cancer cells absorb more of the radioactive substance used in the scan.
The lab tests they will do include a complete blood count, a broad chemical test that measures various aspects of your blood, and liver function tests that check how your liver is performing. Also, a pulmonary function test may be necessary to assess how well your lungs work before potential surgery.
A tissue diagnosis or a biopsy, which includes taking a small sample of the tissue in your lung for examination, is necessary to help guide treatment recommendations. This process can involve several methods including a bronchoscopy for tumors in the central part of the lung, biopsy using an endobronchial ultrasound (EBUS) or mediastinoscopy for suspected hilar (the area where the bronchi and blood vessels enter the lung) or mediastinal (area between the lungs) nodes, and CT-guided needle biopsy for tumors on the outer parts of the lung. Some diagnoses can also be made after a surgical removal of the suspected cancer tissue.
Lung cancer, also known as non-small cell lung cancer (NSCLC), can be categorized into stage I, II, III, or IV at the time of diagnosis. Unfortunately, many patients have advanced (stage III or IV) or metastatic disease at the time of diagnosis. The cancer may have spread to distant parts of the body, most commonly the bones, adrenal glands, or the brain at this stage. Survival chances depend on the stage at diagnosis, how well you respond to treatment, and how much treatment your body can handle. Generally, the 5-year survival rate can range from 40% to 70% for stage IA/IB, 30% to 55% for stage IIA/IIB, 5% to 25% for stage IIIA/IIIB, and 1% to 13% for stage IV.
Treatment Options for Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer
If you have early-stage NSCLC and are unable to undergo surgery or choose not to, radiation therapy may be an option for you. Some common forms of radiation therapy used for early-stage NSCLC are stereotactic body radiotherapy (SBRT) or hypofractionated radiation, which involves delivering radiation in larger doses over fewer sessions.
Studies have demonstrated that SBRT can control the growth of lung tumors effectively. When used to treat early-stage lung tumors that are towards the edge of the lungs (peripheral), SBRT has shown to control the growth of these tumors in 89% to 96% of cases. SBRT also works well for tumors that are central, or closer to the heart and lungs, with control rates of 89% at 2 years.
The choice between SBRT and hypofractionated radiation depends on the circumstances. In some scenarios where SBRT is not appropriate, hypofractionated radiation can be used, with effective control rates of around 81% over three years. When it comes to extremely central tumors referred to as ultra-central tumors, things can be tricky due to the location of these tumors near critical structures like the heart and lungs. In such cases, treatment methods have to be careful about controlling the dosage and duration of radiotherapy to minimize risks.
There are ongoing debates and research on whether radiation is as effective as surgical therapy. Presently, it’s accepted that radiation therapy can serve as a safe alternative to surgery but whether it’s as good as surgery requires more research. Nevertheless, radiation therapy has the advantage of being less invasive which can be a relief for patients at significant risk from surgery.
Advances have also brought combinations of therapies into the picture. For instance, SBRT combined with a minimally invasive surgery called VATS lobectomy or a resection that removes only a portion of the lung (sublobar resection). Research is also looking into combining radiation therapy and immunotherapy, a treatment that uses the body’s immune system to fight cancer.
A critical part of radiation therapy is delivering accurate and reproducible doses to the tumor site, which is facilitated through a process called CT simulation. This process helps doctors account for the movement of lung tumors during breathing, which can become quite challenging especially for tumors located near the diaphragm. Techniques like 4D-CT, respiratory guiding, abdominal compression, and fiducial marker tracking are used to address this issue.
The location and size of the tumor, as well as the chosen treatment method, will determine the radiation dose received. Therapy for peripheral, central, and ultra-central tumors might differ based on the proximity of these tumors to critical structures like the heart and lungs. The objective is to balance control rates with potential toxicity.
While SBRT is generally tolerable, it’s critical to be cognizant of potential side effects. For example, radiation pneumonitis, a lung inflammation, is common, especially among patients with existing lung diseases. Other complications can include chest wall pain, skin toxicity, and in rarer cases, vascular injury, and spontaneous pneumothorax (an abrupt collapse of the lung). Depending on the tumor’s location, some patients might experience unique complications. For instance, tumors located at the top of the lungs could lead to brachial plexopathy (a condition that causes severe pain in the arm and shoulder) if they receive too much radiation. Even with these potential complications, the balance of the benefits and risks of radiation therapy could be the difference for many NSCLC patients.
What else can Radiation Therapy for Early-Stage Non–Small Cell Lung Cancer be?
When evaluating differential diagnosis, some of the conditions that the doctor should consider ruling out include:
- Bacterial overgrowth syndrome
- Colonic obstruction
- Diverticular bleed
- Gastrointestinal malignancy
- Hemorrhoids
- Inflammatory bowel disease
- Intestinal perforation
- Ischemic colitis
- Malabsorption
- Peptic ulcer disease
- Proctitis and sinusitis
- Small bowel obstruction
