If defining “fastest-killing” cancer is based on which cancer has the worst 5-year relative survival rate, then it would be a tie between pancreatic cancer and malignant mesothelioma (a relatively rare cancer in the U.S. with about 3,000 cases a year).15 However, there are some differences in survival rates for these two cancers, depending on the stage of cancer when it’s diagnosed.

For example, the 5-year relative survival rate for localized pancreatic cancer is 44%, whereas localized malignant mesothelioma is 22%. But when statistics for all three stages are combined (localized, regional, and distant) then both cancers have a 5-year relative survival rate of 12%.1617

Keep in mind that:

  • These survival rates don’t apply later on (after diagnosis) if the cancer grows, spreads, or comes back after treatment.
  • Treatments improve over time, and these numbers are based on people who were diagnosed and treated at least five years earlier.

5 Least Aggressive Cancers

Some of the cancers that are the deadliest can also be least aggressive depending on when they’re diagnosed, meaning the stage of cancer at diagnosis, as well as other factors. This list of least aggressive cancers is defined by 5-year relative survival rates.

Breast Cancer

The 5-year relative survival rate for localized breast cancer is 99%. Localized means there’s no sign that cancer has spread outside of the breast. Relative survival rates compare people with a specific disease to those in the general population without the disease, so in this case people with localized breast cancer are almost as likely to survive for at least 5 years as people without the condition.18

Doctors can isolate and treat these types of breast cancer before they develop into more severe forms of cancer.

Prostate Cancer

Just like breast cancer, prostate cancer can be one of the deadliest cancers, but oftentimes prostate cancers grow very slowly or don’t grow at all, and they’re very treatable. The 5-year relative survival rate of localized prostate cancer is greater than 99%.

Prostate cancers are diagnosed by biopsy and then given a score from two to 10, which indicates how likely it is to spread. Treatment may include watchful waiting, active monitoring with blood tests and biopsies, surgery, or radiation therapy.19

Hodgkin Lymphoma

Hodgkin lymphoma, also called Hodgkin disease, is a type of cancer that starts in the lymph system, which is part of your immune system.20 This type of lymphoma has a 5-year relative survival rate of 89%.21

Although it can spread relatively quickly, it’s also one of the most easily treated types of cancer. The main treatments are chemotherapy alone or chemotherapy followed by radiation therapy.22

Testicular Cancer

For localized tumors in the testicles, the 5-year relative survival rate is 99%. For regional tumors, where cancer has spread to tissues or lymph nodes near the testicles, the 5-year relative survival rate is 96%.23

Treatment will depend on the type and stage of cancer and may include surgery to remove one or both testicles, radiation therapy, and chemotherapy.24

Thyroid Cancer

The thyroid is a gland in the neck that makes hormones to support many bodily functions. The 5-year relative survival rate is 98%.25

Treatment for thyroid cancer may include:26

  • Watchful waiting
  • Surgery to remove part or all of the thyroid gland and lymph nodes
  • Radiation therapy
  • Chemotherapy
  • Hormone therapy to stop cancer cells from growing
  • Targeted therapy to attack specific cancer cells