RET mutation tests detect genetic changes in the RET proto‑oncogene—including germline or somatic point mutations, small insertions/deletions, and gene fusions/rearrangements—that can activate the RET receptor tyrosine kinase and drive cancer growth (most notably medullary thyroid carcinoma, hereditary MEN2 syndromes, and some lung cancers). These tests analyze DNA and sometimes RNA from blood or tumor tissue to identify specific variants and classify them as pathogenic, likely pathogenic, or of uncertain significance.

Clinically, RET test results are used to support diagnosis, assess hereditary cancer risk (if a germline mutation is found), guide prognosis, and determine eligibility for RET‑targeted therapies. They measure the presence of genetic alterations predictive of altered RET function, not direct protein activity or overall tumor burden, so results must be interpreted in the context of other clinical and laboratory findings.

Samples for RET mutation testing are typically collected either as a blood sample or as tumor tissue: a standard venous blood draw is used for liquid‑biopsy tests that analyze circulating tumor DNA (ctDNA), while an existing or new tumor biopsy (formalin‑fixed paraffin‑embedded block or fresh/frozen tissue) can be submitted when available for tumor DNA sequencing.

When the goal is to detect inherited (germline) RET variants rather than tumor‑specific changes, collection is usually whole blood or a saliva/buccal swab to obtain genomic DNA. Collections are performed by a trained phlebotomist or using a supplied saliva/buccal kit and then processed/shipped according to the test provider’s instructions.

A positive RET mutation result means you carry an alteration in the RET gene that can raise your personal risk for certain cancers—most notably hereditary medullary thyroid carcinoma (and, depending on the specific variant, an increased risk of pheochromocytoma and parathyroid disease seen in MEN2 syndromes). A RET mutation found in tumor tissue (somatic) indicates the tumor may be driven by RET and can affect prognosis and treatment choices, while a germline (inherited) RET mutation indicates elevated lifetime risk for affected family members.

A negative RET test lowers the likelihood that RET is the cause of an inherited risk but does not eliminate your overall cancer risk (other genes and non‑genetic factors may still apply). Different RET variants carry different levels of risk and age‑of‑onset, so results are used to guide personalized surveillance, preventive measures, and family testing—discuss your specific result and next steps with your clinician or a genetic counselor.

Clinically, a detected pathogenic RET germline variant is highly predictive of RET-driven disease (e.g., hereditary medullary thyroid carcinoma/MEN2) and guides surveillance and management. A somatic RET alteration in a tumor is a strong indicator of RET-driven oncogenesis and can be actionable with approved RET inhibitors, but negative results do not fully exclude RET involvement (false negatives possible) and low tumor fraction or sample selection (e.g., tissue vs. liquid biopsy) can reduce sensitivity. To maximize reliability, use a validated assay that covers the alteration type sought, consider confirmatory testing for unexpected or low‑allele calls, and interpret results in the context of tumor histology and clinical findings.

How often you should test RET mutation levels depends on the clinical context: germline RET testing (for inherited risk/MEN2) is usually done once for a patient or at key family counseling points, while somatic RET testing of tumor tissue is typically performed at diagnosis of advanced disease or when considering targeted therapy. Circulating tumor DNA (ctDNA) monitoring or repeat tumor genotyping is used to follow treatment response or to look for resistance mutations and is scheduled based on treatment milestones rather than a universal interval.

In practice, clinicians commonly obtain a baseline test at diagnosis, repeat somatic or ctDNA testing at disease progression or before changing systemic therapy, and may monitor ctDNA more frequently while assessing early response (often every 4–12 weeks) or less frequently during stable surveillance (for example every 3–6 months), but exact timing should be individualized. Discuss a testing schedule with your oncologist or genetic counselor so it aligns with your diagnosis, treatment plan, and goals of care.

No — RET mutation test results highlight patterns of imbalance or resilience—not medical diagnoses; they indicate genetic findings or risk signals but do not by themselves confirm the presence or absence of cancer.

These results must be interpreted alongside symptoms, medical history, imaging/pathology, and other laboratory or biomarker data by a qualified clinician to determine clinical significance and appropriate next steps.

You cannot “lower” or reverse a tested RET mutation in your DNA by diet, supplements, or lifestyle — the test result reflects whether the mutation is present in the tumor (somatic) or in your germline DNA. What you can do is use the result to guide care: discuss the finding with your oncologist and a genetic counselor so they can interpret whether the mutation is somatic or inherited and advise next steps.

Clinical actions informed by a RET-positive result include targeted therapies or clinical trials that specifically inhibit RET-driven cancers, tailored surveillance and imaging, and standard cancer treatments as appropriate. If the mutation is germline (heritable), family testing and specialist counseling about risk-reduction options and timing of surveillance or preventive procedures may be recommended. Work with your care team to choose the best plan for monitoring, treatment, and overall health support.