Efficient diagnostic techniques are important in the diagnosis of all forms of cancer, but this is especially true for people who are presenting with symptoms that are indicative of mesothelioma. The disease ranks among the most aggressive malignancies and remains very difficult to treat effectively, especially when a diagnosis is received only in its later stages. A number of studies that have investigated prognostic factors in relation to effective treatments have concluded that an early diagnosis of pleural mesothelioma or peritoneal mesothelioma is among the most important variables in maximizing treatment potential. Thus, efforts to improve a physician’s ability to accurately diagnose the disease are among the most common research projects that are currently underway.

In an effort to add to the available literature on the subject, physicians from the United Kingdom conducted a study to determine the efficacy of using image-guided pleural biopsy techniques in the diagnosis of mesothelioma and other pleural diseases as well. They have recently published their findings in the journal Current Opinion in Pulmonary Medicine and have concluded that image-guided techniques are far superior to the traditional biopsy techniques.

Overview of the Study

When a patient presents with symptoms of mesothleioma, or another pleural disease, the physician will schedule a series of tests to determine the location and makeup of the (possible) disease as presented. Imaging tests will be used to identify the presence of specific physical signs of disease and a biopsy will be conducted for the removal and analysis of actual tissue samples. In cases where fluid from a pleural effusion can be extracted, this fluid can also be analyzed for the presence of malignant cells, but this kind of analysis does not provide the same diagnostic precision as does the analysis of a biopsy specimen. Thus, a definitive diagnosis requires efficient biopsy techniques for the extraction of tissue.

Traditional pleural biopsies have been conducted through either thoracotomy or through “blind” biopsies of the parietal pleura. The former technique provides a clear path to the pleural cavity and the removal of tissue from it, but is a highly invasive procedure that features significant patient burden. A blind biopsy is a much less invasive procedure and can be conducted as an outpatient procedure, but its accuracy is limited because the physician will make the insertion, and subsequent tissue extraction, from outside the patient’s body, without any tools guiding him or her to specific locations in the pleural cavity.

Recent innovations in diagnostic techniques have led to the development of new procedures for diagnosis. Image-guided biopsy refers to the use of imaging technologies to guide the physician in his or her biopsy procedure. Ultrasound and CT are two of the most common technologies used to do this. Ultrasound is beneficial because its feedback is delivered in real time, while CT offers higher resolution than ultrasound does and is able to image structures that ultrasound is not able to. Another recent innovation is video-assisted thoracoscopic surgery, or VATS for short. VATS is a minimally invasive procedure where small incisions are made in a patient’s side and a tiny video camera and specific surgical instruments are inserted. The camera allows the doctor to see the interior landscapes of the patient’s thorax, while the instruments allow whatever procedure is required to be completed. In our discussion here, the instruments would be whatever tools were selected for the biopsy, but VATS can be used for a number of other procedures as well.

In their study, the authors investigated the sensitivity and efficacy of blind biopsy vs. image-guided biopsy in the diagnosis of both pleural malignancies and benign pleural diseases, such as pleural tuberculosis.

Results

The authors found that image-guided biopsy was much more effective in the diagnosis of mesothelioma and other pleural diseases than was blind biopsy. Image-guided techniques allow the physician to choose a location from which to make the extraction, which enables the doctor to select areas that are already displaying signs of disease. This ability significantly cuts down on the chances of a false negative due to poor selection of a sample site. The authors state that their research indicates blind biopsy techniques achieve a diagnostic rate of, at best, 50%, while image-guided techniques demonstrate a success rate well over 80%.

The authors also compared the applicability of image-guided biopsy to that of VATS, or to other thorascopic techniques that doctors may currently use, and they concluded that both sets of techniques exhibited similar diagnostic accuracy, but that the choice of which procedure to deploy should be based on patient status. VATS allows both diagnostic and therapeutic procedures to be performed, but is limited by a need for a clear separation of the pleurae and the presence of pleural fluid to facilitate entry, while image-guided biopsy is a purely diagnostic procedure, but one that can performed in the presence of a fused parietal and visceral pleura. They state that patients who present with large pleural effusions and the need for drainage or pleurodesis should undergo VATS, while patients who present without therapeutic needs, small effusions, and/or with conditions that complicate VATS should undergo image-guided biopsy.

Another consideration that the authors discussed regarding choice of procedure had to do with the potential of mesothelioma to invade biopsy sites, which the disease has a tendency to do. They state that the diagnostic accuracy of a procedure increased with its invasiveness, but so did the chances of the malignancy spreading to the biopsy site. They quote a study that concluded thoracotomy was associated with the highest diagnostic accuracy (100%), but also the highest rate of “tumor-seeding,” (24%), while image-guided was associated with a slightly less accurate diagnostic sensitivity (86%), but a smaller seed potential (5%). However, they state that larger studies are needed before a firm conclusion can be drawn.

Conclusion

The authors conclude their article by recommending that image-guided pleural biopsy, or another innovative procedure such as VATS, should replace blind pleural biopsy whenever possible. They state that it has a much higher diagnostic accuracy than does traditional biopsy, and is safe and effective for the investigation of mesothelioma, and other pleural diseases.

Labels: diagnosis, mesothelioma