Cancer remains one of the leading causes of death worldwide. In 2020 alone, nearly 10 million people died from cancer globally, accounting for nearly one in six deaths. While advancements continue to be made in cancer treatment and early detection, some cancers remain among the deadliest due to their aggressiveness, difficulty to diagnose early, limited treatment options, and other factors.
When looking at cancer mortality rates, these are the top five deadliest cancers:
Lung Cancer
Lung cancer is by far the deadliest cancer worldwide, responsible for over 1.8 million deaths in 2020 alone. This accounts for nearly one in five cancer deaths globally. The 5-year survival rate for lung cancer is under 20% for all stages combined. Part of what makes lung cancer so deadly is that it is often caught late, after it has already spread through the lungs or to other parts of the body. Lung cancer tends to have vague symptoms in its early stages, making it challenging to diagnose early.
The two main types of lung cancer are small cell and non-small cell lung cancer, with non-small cell accounting for around 85% of cases. Non-small cell lung cancer includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. While localized lung cancers have over a 50% 5-year survival rate when caught early, the rate drops dramatically once the cancer spreads. For lung cancers that have spread widely, the 5-year survival rate is only around 5%.
The leading risk factor for lung cancer by far is smoking. Around 80-90% of lung cancer deaths are attributable to smoking cigarettes. Exposure to secondhand smoke, radiation, asbestos, and other carcinogens are also risk factors. Lung cancer risk rises with age, with most cases occurring in those age 55 and older.
Treatment
Treatment options for lung cancer include surgery, chemotherapy, radiation therapy, targeted drug therapy, and immunotherapy. The stage and type of lung cancer determine which treatments will be most effective. Early stage non-small cell lung cancers are often treated with surgery to remove the tumor along with chemotherapy or radiation. Advanced lung cancers are more difficult to treat and usually require a combination of chemotherapy, radiation, and other drugs to try to slow progression.
Prevention
Since smoking is the leading cause of lung cancer, the best way to prevent it is by not smoking or quitting smoking. Avoiding secondhand smoke and limiting exposure to environmental carcinogens is also important. Getting regular screening with low-dose CT scans for those at high risk due to smoking history can help detect lung cancer early when it is most treatable.
Colorectal Cancer
Colorectal cancer, which includes both colon and rectal cancers, is the second deadliest cancer globally. In 2020 it caused over 915,000 deaths worldwide. It accounts for nearly 1 in 10 cancer deaths. The 5-year relative survival rate for colorectal cancer is 65% in the United States, but this depends heavily on the stage at diagnosis. If caught at an early, localized stage, the 5-year survival rate is over 90%. However, only about 4 in 10 colorectal cancers are diagnosed at this early stage.
Colorectal cancer usually develops slowly over many years from precancerous polyps in the colon or rectum. If these polyps are detected early and removed through screening, cancer can be prevented. Screening is key for this cancer as early detection greatly improves survival.
Major risk factors for colorectal cancer include older age, family history of colorectal cancer or polyps, a personal history of inflammatory bowel disease, and lifestyle factors like smoking, obesity, lack of physical activity, a diet high in red meats or processed meats, and moderate to heavy alcohol consumption.
Treatment
Common treatments for colorectal cancer include surgery to remove the tumor along with parts of the colon and nearby lymph nodes, chemotherapy, radiation therapy, and targeted therapy. Which treatments are used depends on the stage. Early stage cancers can often be treated with surgery alone, while advanced cancers require chemotherapy and other treatments. Removing precancerous polyps can prevent cancer from developing.
Prevention
Colorectal cancer can often be prevented through regular screening tests that look for polyps or cancer starting at age 45. Some of the screening options include stool-based tests like FIT or Cologuard done every 1-3 years or direct visualization tests like colonoscopy done every 10 years. Leading a healthy lifestyle with a low fat, high fiber diet, maintaining a healthy weight, avoiding smoking and heavy alcohol intake, and getting regular exercise may also help lower colorectal cancer risk.
Pancreatic Cancer
Pancreatic cancer was the third deadliest cancer worldwide in 2020, responsible for over 466,000 deaths. Pancreatic cancer accounts for about 3% of all cancers but 7% of cancer deaths. It has an overall 5-year relative survival rate of only 11%, reflecting how aggressive and challenging to treat this cancer tends to be.
One reason pancreatic cancer is so deadly is that it is usually not caught until the advanced stages when the cancer has already spread outside the pancreas. Early stage pancreatic cancer typically has no symptoms, so it is rarely caught early. Once the cancer grows and spreads, it causes nonspecific symptoms like jaundice, weight loss, abdominal pain, or back pain that could indicate a number of conditions besides cancer.
Major risk factors for pancreatic cancer include smoking, obesity, old age, family history of pancreatic cancer, diabetes, chronic pancreatitis, and other genetic conditions. The rates of pancreatic cancer have been rising over the past decade linked to increasing rates of obesity and diabetes.
Treatment
Treatment options for pancreatic cancer include surgery, chemotherapy, radiation therapy, targeted therapy, and sometimes immunotherapy. Surgery can be curative if the cancer is caught at a very early stage before spreading, but this accounts for less than 20% of cases. Chemotherapy and radiation can help extend life and control some symptoms but is rarely curative once the cancer has metastasized beyond the pancreas. New immunotherapy drugs are showing some promise in clinical trials but have not yet become standard treatment.
Prevention
Preventing pancreatic cancer is challenging since there are no standard screening tests to catch it early. The best ways to reduce risk are by not smoking, maintaining a healthy weight, getting regular physical activity, and managing diabetes if present. People with a strong family history of pancreatic cancer may benefit from genetic testing and increased surveillance.
Stomach Cancer
Stomach cancer, also called gastric cancer, caused over 769,000 deaths worldwide in 2020, making it the fourth leading cause of cancer death. The 5-year relative survival rate for stomach cancer is only 32% worldwide. In the United States, the 5-year survival rate is about 32% for advanced stomach cancer but as high as 65% for early stage cancers that have not spread.
The early symptoms of stomach cancer can be vague, such as indigestion, bloating, loss of appetite, heartburn or nausea. This can lead to people ignoring the symptoms or attributing them to other conditions. By the time stomach cancer causes more overt symptoms like unexplained weight loss or vomiting blood, it is often already in the later stages.
Main risk factors for stomach cancer include H. pylori bacterial infection, a diet high in salty or smoked foods, smoking, obesity, and family history of stomach cancer. Stomach cancer tends to develop slowly over many years.
Treatment
Treatments for stomach cancer include surgery to remove all or part of the stomach along with nearby lymph nodes and possibly other organs or tissues, chemotherapy, radiation therapy, targeted drugs, and immunotherapy. Early stage stomach cancers have a much better prognosis with just surgery. Later stage stomach cancers require a combination of surgery, chemotherapy, radiation therapy, and other drugs. Unfortunately only about 1 in 5 stomach cancers are diagnosed at an early stage before spreading.
Prevention
Screening for stomach cancer is not routine, but endoscopy screening is sometimes recommended for those at elevated risk including people with H. pylori infection or a family history of stomach cancer. A diet rich in fruits and vegetables and low in salty, smoked, or processed foods may lower stomach cancer risk. Quitting smoking and avoiding tobacco is also important. Treating H. pylori infection with antibiotics can prevent progression to stomach cancer in those who have the bacteria present.
Liver Cancer
The fifth deadliest cancer is liver cancer, or hepatic cancer, which led to over 766,000 deaths in 2020 worldwide. Liver cancer accounts for nearly 3% of cancer cases but has a high fatality rate. The overall 5-year relative survival rate is only 18%. However, when liver cancer is detected in the early stages when surgical removal of the tumor is an option, the 5-year survival rate is over 30%.
Liver cancer often develops silently with vague or no symptoms initially. By the time symptoms like abdominal pain, jaundice, or weight loss appear, the cancer is usually in the later stages. Early detection improves outcomes, but there is still no standard screening method for liver cancer in people at average risk.
The main risk factors for liver cancer include hepatitis B or hepatitis C virus infection, cirrhosis from any cause, non-alcoholic fatty liver disease, obesity, diabetes, aflatoxin exposure, smoking, and excessive alcohol intake. Liver cancer is more common in men than women globally.
Treatment
Treatment options for liver cancer include surgical resection, liver transplant, tumor ablation, embolization therapy, radiation therapy, chemotherapy, and targeted drug therapy. Which treatments are used depends on the size, location, stage, and spread of the cancer as well as underlying liver function. Only around 20-30% of people with liver cancer are candidates for surgical procedures. Targeted therapy with sorafenib is the standard drug treatment for advanced liver cancer when surgery is not an option.
Prevention
Since chronic liver diseases are the biggest risk factor for liver cancer, prevention efforts focus on limiting these conditions. Getting vaccinated against hepatitis B, avoiding behaviors that can spread hepatitis B and C, minimizing alcohol intake, losing weight if obese or overweight, managing diabetes well, and avoiding aflatoxin contaminated foods can all help lower liver cancer risk. Patients with cirrhosis or other liver conditions may need periodic screening to try to detect liver cancer early.
Conclusion
While cancer death rates are slowly declining, cancers of the lung, colorectum, pancreas, stomach, and liver remain among the top causes of cancer mortality worldwide. Prevention efforts to curb smoking and risky alcohol use, increase physical activity, improve diets, and treat precursor conditions can all help lower risk. Advances in early detection and cancer treatments have improved outcomes for many cancers. But these deadly cancers highlighted often present with vague symptoms, spread early, have limited treatment options, or a combination of these factors that lead to low survival rates overall. Continued research into finding ways to detect these aggressive cancers earlier and developing better treatments will be key to improving survival statistics over time.
