Analyzing biopsied cells is a highly accurate method for diagnosing mesothelioma.
A biopsy is a crucial diagnostic procedure doctors use to detect mesothelioma. Biopsies are commonly performed to determine whether a suspicious lesion is cancerous or noncancerous, and can also be used to distinguish the specific type of cancer present. Performing a biopsy is one of the most definitive ways to ensure an accurate mesothelioma diagnosis.
During a biopsy, a surgeon removes a tissue or fluid sample for follow-up analysis. A pathologist then views the sample’s cells under a microscope, which reveals their features, activity and interactions. If mesothelioma cells are observed, the pathologist can determine how far the cancer has spread. Biopsies can also prove when mesothelioma is not the correct diagnosis.
Various methods for biopsy exist, including techniques that use needles, bronchoscopes and surgery to obtain samples. Depending on the invasiveness of the method used, local or general anesthesia may be required.
The type and location of a patient’s mesothelioma tumor dictates which biopsy procedure should be performed. Peritoneal mesothelioma patients commonly undergo a fine-needle aspiration biopsy, while a thoracoscopic biopsy is more effective for patients with pleural mesothelioma. Because 75 percent of all mesothelioma cases are pleural (affecting the outer protective layers of the lungs), the majority of mesothelioma patients receive thoracoscopic biopsies.
A VATS biopsy requires only one small incision at either of the locations pictured above.
Thoracoscopic biopsy has displayed remarkably accurate results for the diagnosis of mesothelioma. Also known as open pleural biopsy, this procedure allows doctors to see into the pleural space and retrieve multiple tissue samples. Most treatment centers offer video-assisted thoracoscopic surgery (VATS), which uses a camera and various small tools to collect samples.
Several studies have reported that a thoracoscopy can make an accurate diagnosis in up to 98 percent of mesothelioma patients. Direct examination of the pleura may also help with determining cancer stage and the patient’s prognosis.
In a 2008 postmortem study of 45 malignant mesothelioma patients, researchers compared the accuracy of several biopsy techniques, including open pleural biopsy, closed needle biopsy and computer tomography (CT)-guided biopsy. Open pleural biopsy displayed the highest diagnostic accuracy, confirming a mesothelioma diagnosis in 95 percent of patients with the disease.
Additional Types of Biopsies
Although thoracoscopy yields superior results compared to other biopsy techniques, the procedure may not always be possible because of the tumor’s location and other complications. Other biopsies that doctors use to diagnose mesothelioma include:
- Fine-Needle Aspiration — A quick and safe procedure, fine-needle aspiration (FNA) biopsies use a long, hollow needle to remove up to 10,000 sample cells for testing. This procedure is preferred for its ability to access hard-to-reach areas without the need for anesthesia. FNA biopsies of a pleural or peritoneal effusion can diagnose mesothelioma with an accuracy of up to 84 percent.
- Thoracentesis — This procedure uses a hollow needle to extract fluid and air from the space between the lungs and pleura. While it is commonly used to remove excess fluid that causes pain and weakens lung function, thoracentesis can also be used to obtain fluid samples for analysis.
- Thoracotomy — A thoracotomy is a type of invasive surgery used to access the lungs, heart, aorta, diaphragm and trachea. For mesothelioma patients, a segmentectomy, or wedge resection, is the preferred type of thoracotomy since it leaves most of the affected lung intact. During the surgery, a wedge-shaped piece of the lung is removed to be tested by a pathologist for cancer.
- Endoscopic Biopsy — An endoscopic biopsy is one of the most common biopsy techniques. This procedure uses an instrument called an endoscope that allows the surgeon to see into the area being sampled. Small forceps attached to the endoscope are used to collect slivers of tissue from a potentially cancerous tumor.
- Incisional (Core) Biopsy— During an incisional biopsy, only a small section of suspicious tissue growth is removed. This is a common procedure when the tumor is easily accessible. Unfortunately, mesothelioma tumors typically do not develop in easy-to-reach locations.
- Excisional Biopsy — In an excisional biopsy, the entire lesion is removed rather than a small tissue sample. This procedure can eliminate the need for a second removal surgery if testing shows the tumor is malignant.