Role of Gender Race and Ethnicity

This article discusses how gender, race or ethnicity affects the early detection and screening of cancer.  There are several different ways this topic can be analyzed and it is very complex.  The following will list different ways demographic factors can affect both the incidence and screening of cancer.

Geographic Differences: There are cancers that are more common in certain parts of the world.  For example, stomach cancer (also called gastric cancer) is much more common in Japan and China than in North American or Europe.  Therefore early detection and screening efforts are much more aggressive in Japan.  If an older man with some heartburn and stomach pain sees a doctor both in Japan and the United States, the doctor in Japan would be more likely to pursue invasive testing like an endoscopy camera to view the stomach.

In this example, it may be easy to assume that the difference is simply in that those in japan are Japanese and have a higher genetic risk for stomach cancer.  When someone moves to North America from Japan, after one generation their family’s risk of gastric cancer drops significantly to about the risk of someone born in North America.  This might cause some to wonder if living in that part of the world has special risk factors such as diet or environmental exposures of some sort.  Emphasis has been placed on the traditional Japanese diet as being a risk for cancer of the stomach and it is thought that if they migrate to North American they will adopt a more western diet and this explains the drop in the incidence of gastric cancer.

It is also possible (and more likely) that there is a combination of factors that account for this geographic difference such as nutritional, environmental and genetic risk factors compounding to influence the development of gastric cancer in Japan. Another such geographic difference exists in cancer of the esophagus.  Cancer of the esophagus occurs as often as 1 in 500 people in areas of China and East Africa.  In contrast, esophageal cancer occurs in about 1 in 10,000 people in Japan or the former Soviet Union.  Reasons for this are speculated to be related to drinking very hot tea or high rates of smoking but clearly there are other forces at work.

Racial Differences

This is a complex subject that has led to much research and speculation about some of the stark contrasts in cancer incidence, screening rates and outcomes between.  This topic could be posed in a number of ways as noted and the subject population could be defined differently as depending on what country and region you are in the term “race” is defined differently.  More simplistically we are all a part of the human race however the natural selective forces that created unique racial phenotypes also helped to cluster certain gene pools.

Anthropologists have taken great efforts to classify gene pools in different ways for example by mitochondrial DNA or by blood types.  Certain genes that are involved with repair of cells or promotion of cancer formation (i.e. tumor suppressor genes and oncogenes) are known to have genetic variants.  People isolated to a particular region of the world may be exposed to similar carcinogens or adopt similar dietary habits that also predispose them to the same types of cancers.

Breast cancer has been analyzed extensively in terms of racial differences for incidence, disease severity and outcomes.  Breast cancer is rare in Asia and Arica where rates are as low as 1 in 50,000 compared with North America, Europe and Australia where rates are higher than 1 in 1,000.  Within the United States the overall rate of breast cancer in Caucasians is higher than African-American Women.  Despite the lower incidence, when breast cancer occurs in African-American women it tends to be more a more aggressive type and have a poorer prognosis.  It was initially thought that these differences might be attributable to socioeconomic factors or poor access to health care.  In other words, it was thought that people who are poor and without adequate medical insurance will not get prompt diagnosis and treatment of a small pre-invasive tumor.  This delay in treatment would then presumably cause a poorer outcome later when that person would only seek medical attention after the tumor had spread to other areas of the body (i.e. metastatic disease).

Recent study in this area says quite conclusively that these differences in cancer outcomes among different races and ethnicities cannot be entirely attributed to socioeconomic status disparities.  Another postulated reason for these differences is that aspects of the healthcare system or medical specialists tend to give more thorough and aggressive care to non-minority patients.  This question has been asked in a number of ways looking at not only cancer treatment but also things such as treatment of heart attack.  There is evidence that these types of differences in distribution of medical treatments do exist and the reasons for this are unclear.

The differences in cancer epidemiology among geographic regions and ethnicity have a large impact on the early detection of cancer.  In areas of the world with a high rate of esophageal cancer such as China or East Africa, screening for this disease should be more aggressive for minor symptoms such as heartburn or swallowing difficulty.  In certain groups of people such as those with fair skin or red hair, screening for melanoma skin cancer should be more aggressive due to the increased susceptibility in this population.


  1. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed.  Chapter 47.  New York, NY: Saunders.
  3. Geographical distribution and racial disparity in esophageal cancer.Pickens A, Orringer MB.Ann Thorac Surg. 2003 Oct;76(4):S1367-9. PMID: 14530066
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.