Malignant gastric neoplasms; hope for the future
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2013
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Current Challenges with their Evolving Solutions in Surgical Practice in West Africa: A Reader
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•81• Chapter 8 Malignant Gastric Neoplasms; Hope for the Future N.A. Adu-Aryee Introduction Gastric cancers are a diverse group of cancers which are known to have a poor prognosis worldwide except in Japan and Korea.1 The predominant cancer type worldwide is the adenocarcinoma arising from mucosa and forms 90 percent of all gastric neoplasms. The two main variants are the diffuse and intestinal types with different presentations and prognosis.2 Lesions also arise from lymphoid tissues which are not native to the stomach but are present because of chronic irritation. The main irritant which is also shared with the adenocarcinoma sub-group is the relatively newly found organism Helicobacter pylori (H pylori).3 In lymphoid neoplasms the lesions are known as Mucosa Associated Lymphoid Tissue (MALT) Lymphomas.4 The muscle layer also contributes its share of malignancy through the interstitial cells of Cajal which are the intrinsic pacemaker cells of the stomach. The resulting tumours formerly thought to be leiomyosarcomas (arising from smooth muscle) are now referred to as stromal tumours hence the term Gastro-Intestinal Stromal Tumours, or GISTs.5 Prognosis for adenocarcinomas of the stomach have been considered as poor except in Japan where the disease is considered a public health problem and so early detection and radical surgery for early lesions give survival rates of over 90 percent.6 This has not been duplicated in other places leading to research into supplementary forms of treatment, some of which have shown statistically significant improvements in survival rates. These modalities include peri-operative chemotherapy7 and postoperative chemoradiation8 and •82• Chapter 8 in some cases targeted therapies against Human Epidermal Receptor II where this is over-expressed.9 The presence of H pylori in the aetiology of MALT lymphomas also lends itself to a therapeutic option of organism eradication in treatment of this condition as part of the armamentarium.10 The GISTs are the group which have been in the forefront of research, targeted treatments for tyrosine kinase inhibitors showing the way.11 There are also a tiny subset of neuroendocrine tumours which are apparently quite chemosensitive. This review will focus on the experience with adenocarcinomas within the Korle Bu Teaching Hospital(KBTH). Adenocarcinomas of the stomach Known to be quite aggressive, these lesions have been known to be detected only when symptomatic and advanced in nature except for countries with early detection or screening policies. The worldwide incidence is not known but in Europe 159,900 cases were reported in 2006 with 118,200 deaths recorded.12 In the USA, 38,780 upper gastrointestinal tumours are projected to occur in 2012, of which 25,610 patients are expected to die.13 Operating theatre records for KBTH in Accra suggest that in 2010, seven patients had partial gastrectomies with three having palliative bypasses for obstruction. In 2011, there were eight gastric resections with three bypasses. These figures suggest that most of the cases are still fairly advanced (Figure 8.1) making curative surgery next to impossible. •83• Malignant Gastric Neoplasms; Hope for the Future Figure 8.1: Advanced gastric cancer observed at gastroscopy Mortality rates for gastric cancers have been known to be high and dependent on stage of occurrence or presentation of the lesions. The incidence worldwide is generally thought to be declining. This has been attributed to changes in food storage patterns and the use of frozen foods rather than salted or pickled foods. Improvements in water supply have also been cited. In Ghana Darko et al.1996 found a significant incidence of H Pylori in gastric pathology including tumours.14 Unpublished data by Archampong, T. (personal communication) in Accra also correlate this finding. Other factors like ingestion of well-done red meat, drinking green tea and familial disease patterns have been cited. The worrying trend however is a relative increase in the number of proximal as opposed to distal tumours in the Western world or in •84• Chapter 8 low-risk areas.15 The implications of having more proximal tumours which seem to behave like distal oesophageal tumours is a relatively poorer prognosis with more extensive surgical procedures and more physiologic stress on the patient. This increase in proximal tumours has been linked to increasing obesity in the general populace together with an increase in the incidence of reflux oesophagitis.15,16 The true reason for these changes in epidemiology is not known. Unpublished endoscopy suite figures for the KBTH for 2010 and 2011 give total endoscopic cancer rates of 47...