Stomach Cancer

 

Stomach Cancer

Nikita Rawat, Dr Lopamudra Das Roy

Published 2021

@BreastCancerHub, All Rights Reserved

 Abstract

Stomach cancer, which is also called gastric cancer, begins when cancerous cells in the stomach start to multiply and grow out of control. Gastric cancer is the fourth most common cancer worldwide and is the second most frequent cause of cancer deaths. Stomach cancer is categorized into two main conditions, hereditary and non-hereditary gastric cancer. Living an unhealthy lifestyle, smoking, chewing tobacco, bad dietary habits, obesity, and drinking may lead to stomach cancer that is not hereditary. Stomach problems like chronic inflammation and infections, such as infections caused by the Helicobacter pylori bacteria also lead to stomach cancers. Hereditary Diffuse Gastric Cancer or HDGC is caused when an individual inherits an inactive copy of CDH1 gene located on chromosome 16. People with this gene are at a much higher risk of being a victim to gastric cancer. HDGC is prevalent in areas where screening technology is scarce. Due to lack of screening and the fact that the symptoms don’t appear until later and more threatening stages, it is hard to diagnose, treat, and completely cure gastric cancer. 

Causes, Risk Factors, and Symptoms (1,2)

Humans can have exposure to certain environmental factors that can lead them to be more vulnerable to stomach cancer. People leading unhealthy lifestyles - a diet high in salty and smoked foods, low in fruits and vegetables, smoking, and increased alcohol intake makes them more vulnerable to stomach related issues including developing stomach cancer. Stomach cancer is more common in men than women and typically occurs more in older people. In early stages it doesn’t always show symptoms and is therefore hard to detect. This disease, although less common in Africa and North America, is more common in East Asia, Eastern Europe and South and Central America. Within the U.S. it is more common in Hispanic Americans, African Americans, Native Americans, and Asian/Pacific Islanders. World development is aiding the decrease in cases worldwide due to refrigeration, allowing fish and meat preservation without salting or smoking. Countries high in fish and salted foods consumption like Iceland, Portugal, Brazil, Japan, and Korea, still have high stomach cancer rates but the number is slowly decreasing. There are certain risk factors that aren’t easy to control within the human body that can lead to stomach tumors and ultimately cancer.

Symptoms of stomach cancer, although not present in the early stages, are known to include poor appetite, weight loss, abdominal discomfort , fluid build-up, heartburn or indigestion, nausea, vomiting, swelling, blood in stool, fatigue and even jaundice. 

Infection with Helicobacter Pylori (3,4)

Helicobacter pylori, more commonly known as H. Pylori is the most common bacterial infection in the world. It enters the human body and causes stomach infections and ulcers, and also, hugely increases the risk of stomach cancer. H. Pylori infections are very common, and more than half of the people in the world get it at some point in their lives but sometimes it can leave behind stomach inflammation and bacteria that can lead humans to be 8 times more perceptible to stomach cancer. Cases of H. Pylori are higher in undeveloped countries and low in developed countries. This is due to overcrowded and unsanitary conditions in undeveloped countries.

People with a history of reflux or ulcers are also more prone to stomach cancer, due to a lack of acid in the stomach and surgeries or medication leading harmful bacteria to cause gastric damage. Stomach polyps that are mostly harmless, adenomatous type polyps are known to cause cancer development in some cases. Other rarer cases of stomach cancer may be caused by pernicious anemia and hypertrophic gastropathy.

Hereditary Diffuse Gastric Cancer (5,6) 

Hereditary Diffuse Gastric Cancer (HDGC) is an autosomal dominant cancer syndrome that increases the risk of an individual getting Diffuse Gastric cancer and lobular breast cancer. It is largely caused by an inactivating mutation in the tumor suppressor gene, CDH1. About 1%-3% of all stomach cancers are hereditary diffuse cancers. 

Diffuse gastric cancer (DGC) causes cells to form in the lining of the stomach. These abnormal cells can grow either one by one or in small clusters and slowly grow out of control and harm other cells and organs around it. This diffuse type of stomach cancer is difficult to diagnose because the cancer is not visible on any types of tests or imaging. Because of this, most cases of diffuse stomach cancer are diagnosed at late stages and extremely difficult to treat.

People in the families that carry the HDGC gene are at an increased risk of developing a diffuse-type stomach cancer. The lifetime risk of developing stomach cancer for these people is about 80%. Females who have the HDGC gene are also at an estimated 60% lifetime risk of developing lobular breast cancer. 

Although some people inherit the gene mutation from their parents, others without the cancer gene but family history of stomach cancer, also have a high probability of developing this disease.

Prevention, Diagnosis and Treatment (7)

The risk of stomach cancer can be reduced by following a healthy lifestyle, eating nutritious food, limiting alcohol intake and staying physically active.

It is hard to detect stomach cancer in early stages since the symptoms are not always present. With increased screening as a preventative measure, this disease can be caught early and treated especially in the undeveloped countries where this disease is more prevalent. This is helpful for people that are at a higher risk due to factors such as pre-cancer changes, genetic composition or even gene mutations.

 With physical examination and risk factor assessments doctors can find signs of stomach cancer. At gastroenterology appointments, doctors perform thorough physical examinations and take blood and stool samples for testing. A diagnosis may also come from imaging tests including: CT or CAT scans, X-rays, PET scans or MRI imaging to find suspected area and extent of cancer development.

Endoscopy with Biopsy is one of the most reliable tests for stomach cancer. The techniques used to conduct the test can detect stomach cancer earlier and lead to easier treatment and higher survival rates.

An endoscope is a small tube inserted in the mouth and down the throat to the stomach. This can show doctors the inner linings of the throat, stomach, and mouth.

Stomach cancer treatment can include chemotherapy, immunotherapy and radiation therapy. The most effective treatment for stomach cancer patients is surgery to remove the cancer. The exact procedure depends on the cancer’s stage, where it is located, and how severe it is. Damaged parts, tumors, and even the whole stomach could be removed. 

Prevention with Family History/HDGC (8)

There aren’t very many ways to surely prevent HDGC or stomach cancer with a family history of the condition. The only way to completely stop HDGC is to have a total gastrectomy, which means having the entire stomach removed. The esophagus and small intestine are connected so that the body can still digest food. If the cancer has already spread, or could have spread to other parts of the body, chemotherapy, radiation, or medications may be suggested.

United States 2021 Stomach Cancer Statistics (9) 

  • About 26,560 new cases of stomach cancer in 2021 (16,160 in men and 10,400 in women)

  • About 11,180 deaths from this type of cancer in 2021 (6,740 men and 4,440 women)

  • The average age for getting diagnosed is 68

  • About 6 out of 10 people diagnosed with stomach cancer are 65 or older

  • Stomach cancer is more common in men where 1 in 96 men get it in a lifetime as opposed to women, where it is only about 1 in 152

  • In the US, stomach cancer cases have been dropping by about 1.5% percent over the past decade, due to less H. Pylori cases and increased use of food refrigeration (leading to less salted foods)

 

Global Stomach Cancer Statistics (10)

  • There are about 870,000 cases every year worldwide and about 650,000 deaths

  • About 60% of cases occur in developing countries 

  • Highest incidence rates come from Eastern Asia, South America and Eastern Europe

  • Stomach cancer cases are slowly declining. European countries like Switzerland have had a drop of 60% in the mortality rate in the past generation

  • Stomach cancer is on track to become a rarer disease worldwide

    Developing Countries (11,12) 

         Stomach cancer is more prevalent in developing countries. Environmental conditions and limited resources can be factors which can increase the risk of stomach cancer. On top of that, in these developing countries, access to screening and treatment for cancer tend to be scarce and not properly advocated for.

More than half of the yearly cancer cases in the world occur in developing countries, about 7 million individuals, and, an estimated 75% of these 7 million patients have reached the incurable stage of the disease.

References 

(1) V;Brenner, H;Rothenbacher, D;Arndt. “Epidemiology of Stomach Cancer.” Methods in Molecular Biology (Clifton, N.J.), U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/19107449

(2) “Stomach Cancer - Symptoms and Causes.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 27 Apr. 2021, www.mayoclinic.org/diseases-conditions/stomach-cancer/symptoms-causes/syc-20352438.

(3) Bernstein, Susan. “How H. Pylori May Cause Stomach Cancer.” WebMD, WebMD, www.webmd.com/cancer/hpylori-stomach-cancer.

(4) “Antimicrobial Resistance Incidence and Risk Factors Among Helicobacter Pylori–Infected Persons, United States - Volume 10, Number 6-June 2004 - Emerging Infectious Diseases Journal - CDC.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, wwwnc.cdc.gov/eid/article/10/6/03-0744_article

(5) Blair, Vanessa R, et al. “Hereditary Diffuse Gastric Cancer: Updated Clinical Practice Guidelines.” The Lancet. Oncology, U.S. National Library of Medicine, Aug. 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7116190/.

(6) Willaims, Sarah C.P. “Hereditary Diffuse Gastric Cancer (HDGC): Causes, Symptoms, & Treatment.” WebMD, WebMD, www.webmd.com/cancer/hereditary-diffuse-gastric-cancer-overview

(7) “Stomach (Gastric) Cancer.” Johns Hopkins Medicine, www.hopkinsmedicine.org/health/conditions-and-diseases/stomach-gastric-cancer.

(8) Yaghoobi, M, et al. “Family History and the Risk of Gastric Cancer.” British Journal of Cancer, Nature Publishing Group, 19 Jan. 2010, www.ncbi.nlm.nih.gov/pmc/articles/PMC2816643/.

 (9) “Stomach (Gastric) Cancer Key Statistics.” American Cancer Society, www.cancer.org/cancer/stomach-cancer/about/key-statistics.html.

(10) “Global Cancer Rates Could Increase by 50% to 15 Million by 2020.” World Health Organization, World Health Organization, www.who.int/news/item/03-04-2003-global-cancer-rates-could-increase-by-50-to-15-million-by-2020.

(11) “Cancer Is on the Rise in Developing Countries.” News, 19 Feb. 2014, www.hsph.harvard.edu/news/magazine/shadow-epidemic/.

(12) Olivier. “Cancer: An Impeding Health Crisis in Developing Countries.” Humanium, 7 May 2019, www.humanium.org/en/cancer/.

 



 
Lopamudra Das Roy