Thyroid cytology reports

Molecular Testing for — an Indeterminate Thyroid Biopsy

An indeterminate thyroid biopsy does not mean cancer is confirmed. It means the cells examined could not be clearly called benign or malignant. Molecular testing can answer that question from the same sample — and for many people, that answer spares them surgery.

Medically reviewed by Dr. Mohammed Imaduddin, Surgical Oncologist, MBBS · MS (General Surgery) · M.Ch (Surgical Oncology) · Last reviewed September 2026

Indeterminate does not mean cancer — Bethesda III and IV mean cytology was unclear, not that cancer is present.
Surgery is not the only next step — Molecular testing on the existing biopsy sample can reclassify the nodule without an operation.
A benign result is meaningful — A benign molecular result allows most people to move to surveillance instead of the operating theatre.
Available in India, but not everywhere — Testing is done at select centres; some samples are sent to international reference labs.

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An indeterminate thyroid biopsy — Bethesda III or IV — means cytology alone cannot tell whether your nodule is benign or malignant. Molecular testing analyses the nodule's genetic material to reclassify the result. A benign molecular report allows most people to avoid a hemithyroidectomy and continue with surveillance instead.

What do the terms in an indeterminate thyroid report mean?

Bethesda III — AUS/FLUS: Atypia of Undetermined Significance or Follicular Lesion of Undetermined Significance. The cells looked abnormal but the cytologist could not call them benign or malignant. ATA and TBSRTC guidelines place this category in a risk range that is concerning enough to evaluate further but generally low enough to make surgery a disproportionate first response.
Bethesda IV — FN/SFN: Follicular Neoplasm or Suspicious for Follicular Neoplasm. The cell pattern resembles a follicular growth, but cytology cannot tell whether it is a benign adenoma or a follicular carcinoma — both look identical under the microscope. This category carries a higher malignancy risk than Bethesda III and has traditionally prompted surgery.
Molecular testing: Laboratory analysis of DNA and RNA from your biopsy material to identify genetic alterations — mutations, gene fusions, or expression patterns — that are associated with thyroid cancer. The aim is to reclassify an indeterminate result as more likely benign or more likely malignant.
Afirma Gene Sequencing Classifier (GSC): A commercially available molecular test that uses gene expression data to classify an indeterminate nodule as 'benign' or 'suspicious for malignancy'. Developed and validated in the US, it is used at some Indian centres and international reference laboratories.
ThyroSeq v3: A next-generation sequencing panel that detects mutations and gene fusions most commonly found in thyroid cancers, including BRAF, RAS, RET, and NTRK alterations. It reports a molecular cancer risk score alongside the detected alterations.
Hemithyroidectomy: Surgical removal of one lobe of the thyroid. Traditionally performed when cytology is indeterminate, because the excised lobe gives a pathologist a definitive benign or malignant diagnosis. Molecular testing was developed specifically to identify who actually needs this operation.

What to check before accepting surgery for an indeterminate result

Confirm which Bethesda category your report shows — III and IV have different risk profiles and may follow different pathways.
Ask your cytologist or pathologist whether the stored biopsy sample has enough material remaining for molecular testing.
Find out whether your hospital offers molecular testing directly or whether you need a referral to a centre that does.
Discuss whether your nodule's ultrasound features or your clinical risk factors affect the decision to test.
Consider asking for a second cytology review by a high-volume thyroid pathologist before paying for molecular testing.
Do not book surgery solely because the report says 'indeterminate' without first discussing molecular testing with an endocrinologist or thyroid surgeon.

Repeat FNA, hemithyroidectomy, and molecular testing: how do they compare?

	Repeat FNA	Hemithyroidectomy	Molecular testing
What it involves	A second fine needle aspiration, usually after 3–6 months	Surgery to remove one thyroid lobe under general anaesthesia	Genetic analysis of material from your original FNA — usually no new procedure needed
What it tells you	Whether cytology has changed; may return indeterminate again	A definitive benign or malignant diagnosis from the whole lobe	The probability of malignancy based on the nodule's genetic profile
Main limitation	A second indeterminate result leaves the question unanswered	Removes tissue that may have been benign and was not needed	'Suspicious' does not confirm cancer; surveillance continues even after a 'benign' result
Availability in India	Widely available	Widely available	Limited to select centres; some samples are sent to international reference labs

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Is molecular testing for thyroid nodules available in India?

Molecular testing for indeterminate thyroid nodules is available in India, but it is not yet routine across most hospitals.

A small number of tertiary centres and private oncology units offer access to Afirma GSC or ThyroSeq v3 — sometimes by sending FNA material to reference laboratories abroad. Transit requirements and additional processing time mean you should ask about logistics before committing.

Indian academic centres are increasingly building in-house next-generation sequencing panels that test for the same mutations. Clinical validation from Indian cohorts is still growing, but the mutation profiles of common thyroid cancers are largely consistent across populations.

If your hospital does not offer molecular testing, ask explicitly whether a referral is possible before agreeing to proceed with surgery.

Costs, samples, and what results actually mean

How much does molecular testing cost?

Molecular testing costs significantly more than the FNA itself and more than a standard repeat biopsy. The figure varies by which test is ordered, whether the sample is processed locally or sent to an international laboratory, and whether your insurer covers it. Costs change with laboratory contracts and currency rates, so ask the laboratory for a current written estimate before you agree. A small number of private insurers in India are beginning to cover this test — check your policy or call the insurer with the test name and the laboratory's billing code in hand.

What does a 'suspicious' molecular result mean — does that confirm cancer?

A suspicious result increases the likelihood that the nodule is malignant, but it does not confirm cancer. The definitive answer still comes from the surgical specimen examined by a pathologist after the lobe is removed. What a suspicious molecular result does is give your surgeon and endocrinologist more information before the operation — it strengthens the case for surgery rather than continued surveillance, and it may influence which surgical procedure is planned. Your oncologist will explain what the specific alterations detected mean for your situation.

Can the same FNA sample be used, or will I need another biopsy?

Molecular testing is usually done on material from your original FNA. However, the sample must have been preserved correctly — some tests require the cells to be placed in a specific preservative medium at the time of biopsy, not just fixed on a glass slide. If your biopsy was not prepared with molecular testing in mind, the stored material may not be suitable. Ask your cytologist whether the existing sample is usable before booking a new procedure. If it is not, a repeat FNA with the correct preparation protocol is the next step.

What if the lab says there is not enough material for molecular testing?

An insufficient sample for molecular purposes is a separate problem from the original indeterminate cytology result. If there is not enough RNA or DNA in the stored material, the test cannot produce a valid result. Options are: repeating the FNA with explicit instructions for preserving the sample in the appropriate transport medium, or proceeding to diagnostic surgery as the alternative path. A centre with high thyroid biopsy volume is more likely to have the correct sample preparation protocols in place from the outset.

Is a second cytology opinion worth getting before molecular testing?

Yes, and it costs far less. A second review of the same slides by a pathologist who reads a high volume of thyroid cytology sometimes reclassifies an indeterminate result as clearly benign or clearly malignant — resolving the question without any molecular test. This is recommended before molecular testing in several published guidelines, including guidance from the British Thyroid Association. It is worth pursuing whenever the original report came from a centre with lower thyroid volume, or when there is any uncertainty about how the biopsy was prepared or read.

Did you know?

Most thyroid nodules removed surgically for an indeterminate biopsy are found to be benign on final pathology — the operation answered the question but was not needed to treat cancer.

Molecular testing was developed specifically to identify that group before any surgery takes place.

Source: American Thyroid Association Guidelines for Thyroid Nodule Management (2015, updated guidance 2023)

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Common questions

Frequently asked questions

Can molecular testing completely rule out thyroid cancer?

A benign molecular result substantially lowers the probability of malignancy, but it does not reduce the risk to zero. ATA guidance is that a benign result is sufficient to recommend surveillance — regular ultrasound follow-up — rather than surgery for most patients. Your endocrinologist will set the follow-up interval based on the result alongside the ultrasound features of your nodule. If the nodule grows significantly during surveillance, the question about surgery will be revisited.

My doctor has already recommended surgery — should I ask about molecular testing first?

It is entirely reasonable to ask. Bring the question to your endocrinologist or thyroid surgeon: ask whether molecular testing applies to your Bethesda category and nodule size, and whether it is accessible for your case. A recommendation for surgery may be based on other factors — nodule growth on ultrasound, clinical risk features, or local unavailability of testing — that remain valid even after the conversation. What matters is that the question was asked and answered by someone who knows your full picture.

Which molecular test is better — Afirma GSC or ThyroSeq v3?

Neither has been shown to be definitively superior for Indian patients — direct head-to-head studies in Indian cohorts do not yet exist. Both are validated and widely cited, with different technical approaches. The test your centre uses is usually the one they have established protocols for, which matters for sample preparation, quality control, and result interpretation. The more important question is whether the centre has experience guiding clinical decisions from whichever test they offer.

How long does it take to get a molecular test result?

For tests processed locally in India, results typically take one to two weeks from when the laboratory receives the sample. If the sample is sent to an international reference laboratory, allow additional time for shipping and customs clearance — your centre will give you the current turnaround estimate. A result that takes longer does not indicate a problem with the sample; it usually reflects the laboratory processing queue.

Does CION offer molecular testing for thyroid nodules?

Your oncologist or endocrinologist at CION will advise whether molecular testing applies to your case and coordinate access to the appropriate laboratory. Because testing availability and which assay is most appropriate both depend on your specific report and nodule characteristics, this is best discussed at your appointment. CION works with partner laboratories for specialist testing of this kind.

If molecular testing shows 'benign', do I still need any follow-up?

Yes. A benign molecular result changes the recommended pathway from surgery to active surveillance — it does not discharge you from follow-up. ATA guidance recommends ongoing ultrasound monitoring at intervals your endocrinologist will determine, typically annually to begin with. If the nodule grows or new features appear on ultrasound during that period, the decision is revisited. Surveillance is active monitoring, not no monitoring.

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