Chapter 4: Cancer incidence in Canada: trends and projections (1983-2032) – Stomach cancer - HPCDP: Volume 35, Supplement 1, Spring 2015

Chapter 4: Projections by Cancer Site

3. Stomach cancer

Stomach cancer (sometimes referred to as gastric cancer) was responsible for approximately 1.9% of all incident cases of cancer in Canada in 2003–2007 (Tables 4.3.1 and 4.3.2). It is the tenth most common cancer in males and the fifteenth most common in females. One in 73 males and 1 in 127 females can expect to be diagnosed with stomach cancer in their lifetime, and 1 in 111 males and 1 in 195 females can expect to die from it.^{Endnote 1} On average, 1925 and 1080 new cases of stomach cancer were diagnosed each year in males and females, respectively, during 2003–2007.

The overall incidence rate of stomach cancer in Canada has decreased for a long time (Figure 4.3.1). In 1998–2007, the incidence rate of stomach cancer was the second most rapidly decreasing of all cancers after larynx (2% per year in males and 1.6% per year in females) (Figures 3.1 and 3.2). Stomach cancer has a poor 5-year relative survival rate, at 23% in males and 28% in females in 2006–2008.^{Endnote 1}

The incidence rates increased with age from 0.7 per 100 000 in males aged under 45 to 113.5 in those aged 85 or older, and from 0.6 to 55.1 per 100 000 in females for the same age groups (Tables 4.3.3 and 4.3.4) in 2003–2007. Most people diagnosed with stomach cancer are 65 or older (65% in men and 70% in women). The male-to-female ratio of rates approximated 1:1 in those younger than 45 and increased to 1.9:1 to 2.7:1 in the over-45-year age groups in 2003–2007.

From 2003–2007 to 2028–2032, ASIRs of stomach cancer for Canada are expected to decrease by 30% in males, from 11.1 to 7.7 per 100 000, and by 24% in females, from 4.9 to 3.7 per 100 000 (Tables 4.3.3 and 4.3.4). With the projected Canada population growth and aging, however, the annual number of male cases is predicted to rise by 39%, from 1925 to 2680, and the number of female cases is predicted to rise by 32%, from 1080 to 1425 (Tables 4.3.1 and 4.3.2). The projected long-term trends in males and females show a tendency toward a convergence of rates in each age group (Figure 4.3.2). Elevated rates are reported for the Atlantic region, with the highest rates in Newfoundland and Labrador, but the long-term trends indicate a convergence of rates in regions as well (Figure 4.3.1).

Comments

The gram-negative bacterium Helicobacter pylori (H. pylori) is a major risk factor for stomach cancer. In addition, dietary habits, tobacco smoking, alcohol, genetic factors, occupational exposure to dusty and high temperature environments, Xradiation, gamma-radiation and socioeconomic factors contribute to stomach carcinogenesis. ^{Endnote 47, Endnote 79}

Elevated risk for stomach cancer has been linked to diets rich in starch, poor in protein quality, and poor in fruits and vegetables.^{Endnote 79} A meta-analysis of prospective studies found that stomach cancer risk increases with increasing salt intake.^{Endnote 80} High salt intake may cause damage to gastric mucosa and help H. pylori colonization. ^{Endnote 79} Dietary nitrate can also increase stomach cancer risk, as it may result in endogenous N-nitrosation.

Since the early 1960s, annual per capita fruit and vegetable consumption rates in Canada have increased by over 30%, from 84 kg of fruits and 139 kg of vegetables in 1963 to 132 kg of fruits and 179 kg of vegetables in 2009.^{Endnote 81} The decrease in stomach cancer incidence rates may be attributable to improved healthy lifestyles such as decreased smoking^{Endnote 42, Endnote 43} and changes in diet,^{Endnote 82} and more recently to the increased recognition and treatment of H. pylori infection.^{Endnote 83}