Adjuvant radiation therapy is a common and important component in an overall, multimodal mesothelioma treatment plan. It involves administering some form of radiation treatment after surgical treatment procedures complete. “Adjuvant” derives from the Latin term “to help”. Radiation therapy in mesothelioma cases is not intended to cure the disease or act on its own. Rather, adjuvant radiation therapy helps to control cancer cells and improve the effectiveness of other multimodal treatments like surgery and chemotherapy.
Adjuvant Radiation Therapy Overview
Mesothelioma is a rare and aggressive cancer form. It involves cancerous cells taking hold in the mesothelium—the internal lining surrounding the lungs, abdomen, heart and testicles. Pleural mesothelioma refers to the lungs, peritoneal mesothelioma affects the abdomen, pericardial mesothelioma refers to the heart and testicular mesothelioma involves the testes.
All mesothelioma forms are caused by asbestos exposure. Currently, there’s no cure for mesothelioma. This fatal disease can only be managed through intervention techniques like adjuvant radiation therapy.
Approximately 70-75% of mesothelioma cases are pleural. Around 20% involve periodontal mesothelioma while very few patients experience pericardial or testicular mesothelioma. Accordingly, adjuvant radiation therapy is more common for pleural mesothelioma than peritoneal cases. There is little research available about adjuvant radiation therapy for pericardial and testicular diseases.
Treating malignant mesothelioma is conventionally planned through a multimodal approach. That involves two or more treatment methods working together with each technique doing its part to reduce tumor size and spread. Treatment also requires a multidisciplinary team including oncologists, surgeons, radiologists, specialized assistants, trained nurses and social support workers. Traditionally, the team employs drug-based chemotherapy and surgical intervention followed by adjuvant radiation therapy to kill remaining cancer cells.
What is Adjuvant Radiation Therapy?
Adjuvant radiation therapy involves using radiation techniques after surgery is complete. The main purpose of after-the-fact radiation is killing off remaining cancer cells so they don’t regrow and spread. Radiation involves high-intensity light beams aimed directly at localized cancer cells. Adjuvant radiation can be given after a pleural tumor is removed from the lung or after a peritoneal tumor is taken from the abdomen.
Radiation works by destroying cancer cells’ DNA. Radiation oncologists use Gamma Rays for high-dose radiation treatment and X-Rays for lower and safer applications. Radiation effectively scrambles mesothelioma cell DNA, making it impossible for biological information to be passed on during runaway cell division. Once cells stop communicating, they cease to expand and then die off.
Adjuvant Radiation Therapy Techniques
Traditionally, adjuvant radiation therapy for mesothelioma tumors is used because there are far less active cancer cells to control once surgery completes. Radiation is a dangerous procedure requiring precise aim, timing and repetition. Healthy tissue adjacent to tumors easily suffers collateral damage. Wrong radiation application can do more harm than good.
Radiation therapy involves two distinct procedures:
1. External Beam Radiation Therapy
The most common adjuvant radiation technique, direct beam radiation therapy happens when external radiation is applied by a machine using a linear accelerator, shooting photon beams through the body and at the cancer cells. There have been significant advances in the last decade moving from two-dimensional accelerators to 3-D models, including Intensity-Modulated Radiation Therapy (IMRT). The new equipment is far more accurate than antiquated machines, and they cause far less incidental damage to healthy cells.
Brachytherapy is an innovative procedure that involves placing radioactive devices inside the body, situating them next to the tumor and renegade cells. Some capsules are robotically placed through video-controlled instruments. Others use direct surgical incisions. Brachytherapy devices can be temporary installations, or they can be permanent—depending on the treatment team’s intention.
What Are the Goals for Adjuvant Radiation Therapy?
Adjuvant radiation therapy involves “cleaning up” after tumor tissues are surgically removed. This is opposite of neoadjuvant radiation therapy where tumors receive radiation to stop or shrink them before surgery. After-the-fact radiation is much more common in neoadjuvant intervention.
Goals for adjuvant radiation therapy include:
- Killing Remaining Mesothelioma Cells: It’s rare, if not impossible, for surgeons to remove all active cancer cells. Mesothelioma is a complex cancer form that extends to areas having no clear bounds. Pleural and peritoneal tumors usually have wide spreads and deep reaches. Therefore, oncology teams rely on adjuvant radiation to kill those cancer cells that invariably remain.
- Prevent Seeding: Seeding refers to cancer cells accidentally spread during a surgery. Removing a tumor requires surgical incisions in the skin, muscle and surrounding tissues. That requires contact with cancerous cells, which are transferred to healthy tissue. Accidental seeding causes cancer cells to grow in previously uncontaminated areas. Adjuvant radiation therapy kills seeded cells.
- Improving Remission Rates and Postponing Recurrence: There is no known cure for mesothelioma, as yet. This disease can only be managed through multimodal plans involving chemotherapy, surgery and adjuvant radiation therapy. Administering radiation after surgery vastly reduces active cancer cells. This improves remission rates and postpones recurrence (when the mesothelioma comes back after treatment).
- Palliative Symptom-Control: Adjuvant radiation therapy is highly effective for reducing pain and discomfort associated with mesothelioma. Killing cancer cells allows a patient much better palliative care. Radiation extends patient survival rates and allows a more comfortable quality of life.
Adjuvant Radiation Therapy with EPP
Surgically treating pleural mesothelioma involves two main procedures. One is extrapleural pneumonectomy (EPP). The other is called a pleurectomy/decortication (P/D). In EPP procedures, the pleural lining and one entire lung are surgically removed. This is an aggressive act, and used in advanced mesothelioma stages. Adjuvant radiation therapy is applied after EPP to kill or control cancer cells not removed during surgery.
Adjuvant Radiation Therapy with P/D
Pleurectomy/decortication (P/D) is less traumatizing for the patient. P/D procedures involve removing only the parts of the pleural mesothelium and lung organ containing cancer cells. P/D is best suited to early-stage pleural mesothelioma. Adjuvant radiation therapy is used the same way on P/D as it is on EPP surgeries. The goal is to catch remaining cancer cells that surgery missed.
Adjuvant Radiation Therapy with Cytoreduction with HIPEC
Cytoreduction is a surgical procedure associated with peritoneal mesothelioma. It’s where a surgical oncologist removes or debulks the cancerous portion of the abdomen lining. Often, this operation is immediately followed by an adjuvant technique called Heated Intraperitoneal Chemotherapy (HIPEC). This involves placing a heated radioactive liquid in the abdominal cavity immediately after surgery to wash out and kill remaining cells.
Adjuvant Radiation and Survival Rates
Without question, using adjuvant radiation therapy in conjunction with other multimodal cancer treatments such as surgery and chemotherapy are extending and improving patient lives. Survival rates indicate a patient receiving a multimodal treatment for pleural and peritoneal mesothelioma can have between two and five years added to their lives.
Survival rates vary between cases. The primary aim of adjuvant radiation therapy is to decrease the rate of cancer return (recurrence). That’s dependent on the type of mesothelioma, the stage it’s diagnosed in and the patient’s general health. Survival rates also depend on the type of adjuvant radiation therapy applied.
Adjuvant Radiation Therapy vs. Neoadjuvant Therapy
Adjuvant and neoadjuvant radiation therapies are considerably different. While adjuvant therapy refers to applying radiation techniques postoperative, neoadjuvant therapy is applied before surgery. Both techniques are designed to help in the overall treatment program. However neoadjuvant radiation therapy serves a proactive purpose.
Neoadjuvant radiation is almost always used in pleural mesothelioma cases where the extrapleural pneumonectomy (EPP) surgical technique is intended. Massive radiation bursts are applied to the lung and pleura to stop and shrink the tumor before physical surgery. Once this is done, it’s too late to turn back as the entire lung will be destroyed by radiation.
Seeking Multimodal and Adjuvant Therapy
Adjuvant radiation therapy is highly effective when used in a multimodal approach as part of a multidisciplinary oncology team’s overall mesothelioma management plan. This team considers what’s best for a particular patient and introduces the best adjuvant radiation therapy technique to match other interventions. Top quality teams at leading mesothelioma treatment centers also include their patient in every step of the program.
To learn more about undergoing radiation therapy for mesothelioma, contact our Patient Advocates today.