INVESTIGATION OF THE ANTI-NEOPLASTIC EFFECT OF TRISHUL (AYURVEDIC AGENT) ON TUMOUR REGRESSION OF RECTAL CANCER- A PILOT STUDY

Introduction

Colorectal cancer is now the third-most common cancer in the world and the second-most common cause of cancer death (1). In Sri Lanka, in 2008, colorectal cancer was the 7th most-common cancer (2); in 2021, colorectal cancer had risen in order to be the third-most frequently occurring cancer in Sri Lanka (3,4).

The rectum is the most frequent site of occurrence of cancer and may be found in up to 60percent of Sri Lankan patients with colorectal cancer (2). Treatment of rectal cancer has evolved over the years from complete removal of the rectum with tumour and the anal canal with its sphincters resulting in a permanent colostomy in the 1950s (5), to preservation of the anal canal and the anal sphincter complex resulting in the ability to restore intestinal continuity and avoid a permanent colostomy since the latter part of the 1990s (6,7). Following surgical resection of rectal cancer by anterior or low anterior resection, and restoration of intestinal continuity, the majority of patients experienced impaired continence and soiling which took up to 2 years to improve (8). A lesser proportion of patients, however, were left with long-term soiling that required the use of a protective garment such as a pad. Despite these disadvantages, for South Asian patients, an operation for rectal cancer that restored intestinal continuity and avoided a permanent stoma was encouraging because of the social taboos that were, and are still, associated with a permanent colostomy, and the cost of stoma appliances (9,10).

Local recurrence of rectal cancer following curative surgical resection remained a problem following seemingly surgical successful treatment of patients with rectal cancer that was reported in up to 30percent of patients with rectal cancer (11,12). Following refinement of surgical technique (6), globally, local recurrence rates for rectal cancer were reduced to less than 10 percent and is now the standard of care (13). The use of preoperative chemoradiation to induce size reduction and tumour margin regression, and therefore, a cancer-free margin of resection of the rectum was established in a randomized controlled trial in 2004 (14). Pre-operative chemoradiation for locally advanced cancer of the lower rectum (stage T2 with nodal involvement, stage T3 and T4), is now the standard of care for patients with rectal cancer.

It was found that the use of pre-operative chemoradiation for rectal cancer resulted in regression of tumour either in part or whole. We reported rectal cancer regression following long-course chemoradiation in up to 58 percent of our patients with rectal cancer (15). The observation of a complete response of rectal cancer to treatment by preoperative chemoradiation was first proposed by a group in Brazil, in 1998 (16). These authors proposed that, in a small proportion of patients with rectal cancer who received pre-operative chemoradiation (c-RT), it seemed safe to adopt a non-operative "watch-and-wait" approach with close and frequent observation for recurrent cancer, which was subsequently treated by operative resection. Their conclusion was based on a longitudinal study of rectal cancer patients who displayed a pathologically complete response (p-CR) following pre-operative c-RT for over two decades, which showed that there was no difference in overall survival between those who had had a pathologically complete response and no surgical intervention versus those who underwent surgical resection following a complete pathological tumour response (16).