In modern medicine, current treatments for lung cancer can be broadly classified into 4 categories: surgery, radiotherapy (including traditional photon radiotherapy, newer proton radiotherapy, heavy ion radiotherapy, etc.), chemotherapy drugs, and newer drugs (including targeted drugs and immune drugs, etc.).
Radiotherapy is a method of treating tumors using radiation.
In lung cancer, radiotherapy is very widely used. Whether it is small cell lung cancer or non-small cell lung cancer, whether it is early stage lung cancer or advanced lung cancer, doctors will consider using radiotherapy.
The use of radiotherapy in the treatment of lung cancer
- Early stage tumors that are inoperable. Surgery is a common treatment for early-stage lung cancer, but sometimes radiation therapy is a common option in those cases where the tumor cannot be surgically removed because of its size or location, or the patient’s health status prevents it, or the patient refuses surgery.
- After surgery, radiation therapy (often combined with chemotherapy) is used to destroy any cancer cells that may remain after surgery and to reduce the recurrence rate.
- Patients with tumors that are too large for direct surgery. The use of preoperative radiation therapy (often in combination with chemotherapy) allows the tumor to shrink and can facilitate later surgery.
- Targeted treatment of metastatic lesions, such as lung cancer that has metastasized to the brain or adrenal glands.
- Reducing patient symptoms, including pain, bleeding, coughing, and swallowing disorders. For example, when a tumor is blocking the airway, consider using brachytherapy to shrink or eliminate the tumor and reduce the patient’s pain.
Many people do not know the difference between radiation therapy and chemotherapy, but the two are very different in terms of principles and indications. The two are different in principle and application. Radiotherapy, like surgery, is a local treatment and is more effective when the extent or number of lesions is limited, but if the cancer has metastasized extensively, radiotherapy alone will not work and systemic treatments such as chemotherapy drugs, targeted drugs, and immune drugs will be needed.
Radiation therapy has been around for more than 100 years. 1896, the German physicist Röntgen described the discovery of X-rays, which penetrate human tissue and carry high energy, two properties that quickly caught the attention of the medical community. a few months later, doctors began using X-rays to detect cancer, and three years later, Swedish doctors used X-rays for the first time to treat tumors with good results, which was the beginning of radiation therapy.
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Side effects of receiving radiation therapy
Side effects are more pronounced because radiation therapy kills tumor cells while also causing damage to surrounding healthy cells. If you are planning to undergo radiation therapy, it is necessary to understand the possible side effects.
The side effects of radiation therapy vary depending on the site of radiation therapy. Common side effects include fatigue, nausea and vomiting, loss of appetite and weight, skin changes in the irradiated area (e.g., redness, blistering, peeling), and more. These side effects usually fade after treatment.
But in any case, the side effects are bad and can limit the use of radiation therapy. Modern radiotherapy, therefore, is increasingly emphasizing precision strikes, with new technological developments that can irradiate a lower dose of normal tissue around the tumor, and this includes intensity-modulated radiotherapy (IMRT), stereotactic radiotherapy (SBRT), Gamma Knife, and others.
Also, proton therapy, which you hear a lot about nowadays, is also radiotherapy, but with a completely different radiation source. The big advantage of proton therapy is that it has relatively few side effects, but the disadvantage is that it is very expensive, and in many cases the cost effectiveness is questionable. The vast majority of lung cancer patients do not have a need for proton therapy.
In addition to “external radiation therapy” with large instruments, as mentioned earlier, “brachytherapy” is sometimes used in lung cancer to reduce symptoms such as airway blockage. In this treatment, doctors usually place a small radioactive source close to the tumor. Because of the short range of the radiation from the source, the normal tissue around the tumor is exposed to a lower dose.
But regardless of the form, the main principle of radiation therapy relies on high-energy rays to attack cancer cells, destroying their internal molecules, including DNA, and causing cell death.
Subversive new findings
Before, scientists and doctors thought that killing cancer cells directly was the whole value of radiation therapy. If radiotherapy cured the tumor, it must have been because every cancer cell was shined to death.
Under this philosophy, radiotherapy is used a lot for localized tumors and less for advanced metastatic cancers. This is because if there is cancer in multiple places throughout the body, it is impossible to shine a light on every metastatic tumor. And radiotherapy has side effects, so if the risks outweigh the benefits, there’s no need to do it.
But as everyone understands more about the relationship between the immune system and cancer, and more research is being done, things have changed.
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In 1999, an 83-year-old woman in Switzerland was diagnosed with advanced kidney cancer, with a large tumor of 6 cm above the kidney, and it had metastasized to the lungs and lymph nodes, which were covered with metastatic cancer cells. Due to her frailty, diabetes and heart disease, she was inoperable. The doctors finally decided to use stereotactic radiotherapy to attack the huge tumor on top of the kidney, just hoping to improve the quality of life. Other than that, the patient did not receive any other treatment.
There was a strange outcome.
Two years after the radiotherapy, the old woman was still alive, the tumor above the kidney had not progressed, it was still about 6 cm, but amazingly, the dense metastases in the lungs had disappeared!
Why did the lung tumor disappear on its own when it was clear that only the tumor above the kidney was treated with radiation?
This miraculous phenomenon is called the “distal effect of radiation therapy”: when a metastatic tumor is irradiated, the tumor that was not irradiated shrinks.
The advent of the distal effect of radiotherapy has turned everyone’s understanding of radiotherapy upside down. Apparently, radiotherapy not only kills cancer cells directly, but also causes some kind of systemic changes.
This change is now thought to be primarily modulation of the immune system.
The mechanism by which radiation therapy modulates the immune system is complex and not fully understood. But one of the important principles is that when radiation kills cancer cells, it releases “danger signals” that activate the immune system and allow the immune cells to better recognize and remove the remaining cancer cells.
Radiotherapy turns into a local “cancer vaccine”
Since radiation therapy has an important modulating effect on the immune system, can radiation therapy be combined with immune drugs?
Clinically, this is being actively tried.
Animal models and some clinical cases have shown that radiotherapy, especially stereotactic radiotherapy, can significantly increase the effectiveness of immunotherapy. Stereotactic radiotherapy is a relatively new radiotherapy technique that takes less time and delivers higher doses. If conventional radiotherapy is a slow cooker, stereotactic radiotherapy is a big fire.
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The initial advantage of stereotactic radiotherapy was its ability to reduce side effects on normal tissue, but recent studies have found that this “big firestorm” also appears to be stronger in its ability to activate the immune system, killing two birds with one stone.
In just a few years, several “radiation + immunotherapy” clinical trials have been launched around the world for lung cancer, melanoma, prostate cancer, and more. We look forward to their good news.
In summary, radiation therapy is one of the traditional cancer treatments, but new shoots can come from old trees. Both its operational methods, techniques, and theories are rapidly evolving and advancing. Rather than being replaced by newer treatments, radiotherapy will most likely become an increasingly integral and important part of comprehensive lung cancer treatment in the future!