Lytic effects of water on cancer cells: Implications for post‐operative irrigation

Background Intraoperative tumour spillage can be concerning during cancer excisions, given it can lead to tumour‐cell re‐implantation and local recurrence. Examples include bladder tumour recurrences post‐transurethral resection, or peritoneal spillage during laparotomy/laparoscopy for bowel and ovarian cancers. One approach to reducing implantation is mechanical wash out of free‐floating tumour cells. Irrigation with water may have additional effectiveness compared to iso‐osmotic irrigants (e.g. saline) by causing osmotic cytolysis, but this is not well‐characterised. This in vitro study aimed to ascertain the time‐course of osmotic effects of water on various cancer cell lines to provide guidance for clinical usage. Methods Assays were conducted on six cancer cell lines (bladder [HT1197, HT1376], colon [KM12, LIM2405], kidney [SKRC52], and ovarian [COV434]). Cells were exposed to water or 0.9% saline and cell counts were performed using a haemocytometer at 10, 20, 40, 60, 120 and 180 min. Cell viability was determined using Trypan Blue exclusion. Results In all cell lines, exposure to water led to 100% cell lysis within a median time of 40 min (range 10–180 min), while exposure to saline led to a gradual decline in cell viability (median 50.2%, range 6.7%–100.0%) over 3 h, and did not result in complete cell lysis. An increase in osmotic gradient equivalent to a concentration of 5% NaCl was sufficient to impede the effects of water‐mediated cell lysis. Conclusion Our studies suggest that water has a rapid osmolytic effect on cancer cells. The required exposure time to reach 0% cell viability varied between individual cell lines. Post‐operative water irrigation may be more effective than saline irrigation due to additional osmotic cytolytic effects. This in vitro study aimed to ascertain the time‐course of osmotic effects of water irrigation on various cancer cell lines in comparison to normal saline.