What is POLE?


POLE is a gene that provides instructions for making a protein called DNA polymerase epsilon. This protein is very important because it helps copy DNA when cells divide. It also has a special function called proofreading, which works like a spell-checker to make sure mistakes in DNA are fixed. When POLE is working normally, it helps keep our DNA stable and prevents harmful mutations from building up.

What happens when POLE is mutated?

Some people inherit mutations (changes) in the POLE gene, while in other cases the mutations happen only in tumor cells. Mutations that affect the proofreading part of POLE make it harder for the protein to correct mistakes. This leads to the accumulation of many mutations in the DNA, a condition sometimes called ultramutation. Ultramutated tumors often behave differently from other cancers and may respond better to certain treatments like immunotherapy.

Inherited mutations in POLE can cause a rare condition called polymerase proofreading–associated polyposis (PPAP). People with PPAP develop multiple colon polyps at a young age and have a higher chance of developing colorectal cancer.

What types of cancer are associated with POLE mutations?

Mutations in POLE are most commonly found in:

  • Endometrial cancer: About 7 to 12 percent of cases.

  • Colorectal cancer: About 1 to 2 percent of cases.

  • Brain tumors, ovarian cancer, pancreatic cancer, stomach cancer, and skin cancers have also been reported in smaller numbers.

Because POLE mutations make tumor cells accumulate many changes, they can sometimes trigger a stronger response from the immune system. This may explain why POLE-mutated cancers often have a better prognosis compared to tumors without this mutation.

How is POLE tested?

Pathologists can test for POLE mutations using molecular testing, which looks at the DNA sequence of the gene. This is usually done with a technique called next-generation sequencing (NGS), which can check many genes at once. In some cases, more targeted methods such as polymerase chain reaction (PCR) may be used.

Testing is often considered when:

  • A person develops colorectal cancer or endometrial cancer before age 50.

  • A person has multiple colon polyps.

  • There is a strong family history of colorectal or endometrial cancer.

Your pathology report may describe POLE test results as pathogenic (disease-causing), likely pathogenic, or negative if no mutation is found.

Why is POLE testing important?

Identifying a POLE mutation can be helpful for several reasons:

  • It can explain why a cancer developed, especially in younger patients.

  • It can guide treatment, since POLE-mutated cancers may respond well to immunotherapy.

  • It can predict prognosis, as many POLE-mutated cancers have a more favorable outcome.

  • It can identify inherited conditions like PPAP, which may affect family members.

Questions to ask your doctor

  • Was my tumor tested for POLE mutations?

  • If I have a POLE mutation, is it inherited or only in my tumor?

  • How do these results affect my treatment options, such as immunotherapy?

  • Does this mean my cancer has a better prognosis?

  • Should my family members be tested for POLE mutations?

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