A procedure that involves washing heated chemotherapy drugs through the open body cavity after mesothelioma surgery may not be as helpful as some mesothelioma experts had hoped.
A study on hyperthermic chemotherapy perfusion conducted by researchers in the thoracic surgery department at the David Geffen School of Medicine suggests that most mesothelioma cells lines are relatively unaffected by heat. The laboratory study included three kinds of mesothelioma cell lines, along with lung cancer cells, hamster-derived ovarian cells, and normal lung fibroblasts.
First, the growth rate of each type of cell was measured in the lab. Next, to test the impact of heat alone and different types of cells, the cells were exposed to 37, 42 and 45 degrees centigrade for 20, 40 or 60 minutes. The results revealed that some types of cells appear to be more heat sensitive than others. Among the ovarian cells, only 1.5% survived when exposed to the highest heat (45 degrees) for the longest time (60 minutes). In contrast, lung cancer cells showed no response at all unless the highest temperature was used. In the mesothelioma cell samples, 35% of cells were destroyed at the highest levels of heat and duration.
Researchers then exposed each type of cell to three of the most common chemotherapeutic drugs for mesothelioma: cisplatin, gemcitabine and pemetrexed. The test cells were exposed to these drugs with and without simultaneous heat exposure. Each drug was tested by itself or in cisplatin/pemetrexed or cisplatin/gemcitabine combinations. While there was some additional destruction of mesothelioma cells when heat was used, the effects were minimal, prompting the researchers to conclude that “most of the reduction was attributable to chemotherapy and not hyperthermia”.
Unfortunately for mesothelioma patients, none of the mesothelioma cell lines tested showed significant sensitivity to heat and the LA-based research team says the growing popularity of heated chemotherapy may not be warranted. “The use of hyperthermia alone or with chemotherapy produces at best only a modest effect and does not necessarily support its current clinical use,” concluded the authors.
These studies in cell lines may not be a perfect representation of what is happening in mesothelioma patients. For example, perhaps the heat helps enhance a immune response. Possibilities like these were not addressed by this new study.