Why are Cancer rates low at higher elevations

Despite huge advancements in medical science in the last few decades, Cancer still continues to be a major health concern, with no one cure in sight. It is, however treatable if caught early, yet presents a risk of (almost) always coming back, often in a more aggressive form. What makes Cancer so tricky to treat, is that cancer cells do not follow a linear path while multiplying, and spread rapidly, thus defeating most conventional lines of treatment.


Why does cancer happen?
While there is no one reason for cancer, a mix of genetic and lifestyle factors is said to be the culprit. Hence it is important that one takes care of their health to try and keep cancer at bay. However, do you know that cancer rates are lower in higher altitude areas? Yes, that is true. Here's why...

Low cases at higher altitudes
One key study found that lung cancer incidence decreases as elevation increases. For every 1,000 meters rise in altitude, lung cancer cases dropped by about 7.23 per 100,000 people, which is roughly a 12.7% decrease compared to average rates. This effect was second only to smoking habits as a predictor of lung cancer risk. Another study in the United States and China also observed lower cancer prevalence and mortality in high-altitude populations.

What could be the possible reason?

Reduced air pollution has less carcinogens
At higher altitudes, the concentration of particulate matter and air pollution is generally lower. Since air pollution is a known carcinogen, less exposure might mean fewer cancer-causing agents in the environment. Cleaner air could contribute to the reduced incidence of cancers, especially lung cancer.

Hypoxia and its ripple effects
High altitude means lower oxygen levels, a condition called hypoxia. This triggers unique biological responses that may slow down cancer growth or reduce the chance of cells becoming cancerous. Some animal studies showed that tumor growth and metastasis rates were lower under hypoxic conditions similar to high altitudes. Also, chemotherapy might be more effective in such environments.


Radiation Hormesis
Higher altitudes have increased natural background radiation due to thinner atmosphere. Some research suggests this low-level radiation might stimulate protective biological responses, a concept called radiation hormesis, which could help reduce cancer mortality.

Conflicting Findings and Other Factors
However, not all studies agree. Research from Ecuador found that living above 2,000 meters was associated with a higher prevalence and mortality of several cancers, including stomach, colorectal, liver, breast, and lymphatic cancers. This suggests that altitude alone may not be protective everywhere and that other factors like genetics, lifestyle, diet, and healthcare access also play roles.

Socioeconomic and Lifestyle Influences
People living at high altitudes often have different lifestyles — they may smoke less, have more physical activity, or different diets — all of which can affect cancer risk. Socioeconomic factors such as education and healthcare availability also influence cancer outcomes and may explain some differences seen in studies.

Not the only factor
While Lung and some other cancer rates tend to be lower at higher altitudes (due to cleaner air), it needs to be noted that altitude is not the only factor that determines Cancer. Factors like genetics and lifestyle play a huge role in Cancer occurence, no matter where you live. Hence, it is important to practice a healthy lifestyle, eat a balanced diet, exercise, and refrain from alcohol and smoking, in order to prevent yourself from Cancer.

Sources
Cancer risk associated with living at high altitude in Ecuadorian population (PMC)

Thiersch M, Swenson ER. High altitude and cancer mortality. High Alt Med Biol. 2018;19(2):116-123. PubMed

High Altitude and Cancer Mortality - Mary Ann Liebert, Inc. ScienceDirect

Moderate Altitude Residence Reduces Male Colorectal and Female Breast Cancer Mortality MDPI

Clinicopathological characteristics of breast cancer at high altitude Frontiers in Oncology

Relationship of site-specific cancer mortality rates to altitude Oxford Academic