Can a biopsy spread it?

Prepared 3 September 2026 by Kya for a friend, for her partner. Every source below was checked against PubMed or the original publisher page; quotations are verbatim. Where a claim could not be verified it is marked as such. This is not medical advice; it is what the published evidence says, laid out so the question can be put to the patient's team with the right words.

The question, put fairly

Her partner's worry has three parts:

1. Biopsies can spread tumours. Is that true, and how often?
2. Some things in the body are dangerous to puncture, like parasitic cysts. Could this be one of those?
3. Tumours are complex structures; might there be other biological entities inside that get released when it is disturbed?

Each deserves a straight answer. Here they are, in that order, with the evidence, and then a section on where the worry is legitimate.

1. Can a biopsy spread a tumour?

Yes, it can, it is rare, and it has been measured. It is called needle-tract or surgical-pathway seeding, and the medical literature has taken it seriously for forty years. What the numbers show:

Across cancers in general

• Breast. When a core-needle biopsy is followed by surgery, pathologists can find tumour cells pushed along the needle track in about a third of specimens. But the proportion falls the longer the gap between biopsy and surgery (42% under 15 days, 31% at 15 to 28 days, 15% after 28 days), and the authors' conclusion was: "This relation suggests that tumor cells do not survive displacement." (Diaz 1999, 352 patients.) A systematic review found displaced cells in 22% of specimens and "No increase in local recurrence was reported after CNB." (Liebens 2009.) In 4,405 women, seeding was confirmed in 3.0%, and the recurrence rate in the breast was no different between those with and without it (Maseki 2023). In 1,525 women followed for a median of 9.5 years, core biopsy "did not have an adverse effect on survival outcomes" (Liikanen 2016).
• Liver cancer has the highest reported seeding rate of any common tumour: 2.7% overall in a meta-analysis (Silva 2008). Yet in 309 patients listed for liver transplant, of whom 80 had been biopsied, recurrence (9.3% vs 8.9%) and 5-year survival (60% vs 61%) were identical, and the authors wrote "there is no argument to restrict biopsy in doubtful situations." (Fuks 2014.)
• Lung. In a survey covering 68,346 needle biopsies, eight cases of track metastasis were reported: 0.012% (Ayar 1998). One series found 0.56% (Ibukuro 2009); another found none, and no increase in cancer cells in the fluid around the lung (Sano 2009).
• Pancreas. In 2,034 patients in the US cancer registry, those who had a needle biopsy before surgery had no worse cancer survival than those who did not (Ngamruengphong 2015).
• Bone and soft-tissue sarcoma, the tumour family closest to chordoma. In 180 patients, the biopsy track was contaminated in 0.8% of needle biopsies and 32% of open surgical biopsies (Barrientos-Ruiz 2017). Contamination did matter when it happened: recurrence-free survival was much shorter. The lesson the authors drew was to use needle biopsy and to do it at the treating centre. The classic paper on biopsy hazards in sarcoma (Mankin 1996, 597 patients) found that "Errors, complications, and changes in the course and outcome were two to twelve times greater when the biopsy was done in a referring institution instead of in a treatment center." The harm was from badly planned biopsies at the wrong hospital, not from the act of sampling.

The pattern

Cells can be found along a needle track under the microscope. Clinically visible seeding is rare (roughly 1 in 10,000 for lung, 1 in 1,000 for abdominal fine-needle biopsies, 1 in 100 for needle biopsy of sarcoma, about 3 in 100 for liver cancer). And in every large human study that has looked, people who had a biopsy did not die sooner or recur more than people who did not. Where biopsy has been shown to do harm, the cause identified by the authors was a badly placed or badly performed biopsy outside a specialist centre.

Chordoma specifically

This is the tumour the team suspects, and it has its own seeding literature, which is worth reading carefully because the numbers are often quoted without their context.

• After endoscopic (through-the-nose) operations, the Pittsburgh group, one of the highest-volume chordoma centres in the world, reported 2 seeding events in 173 operations (1.15%) (Fernandes Cabral 2018), updated to 3 in 271 operations (1.1%) over twenty years (Gersey 2026). Both papers describe seeding after full tumour removals, not after biopsies. The mechanism they identified was "decreased visualization during tumor removal combined with mucosal trauma": cells carried onto raw nasal lining during a long operation to take the tumour out.
• After open (through-the-skull) operations, the rate is higher: 2.8% in the pooled published cases (Iloreta 2014), up to 7.3% in one series of 82 patients (Arnautović 2001), where cells even turned up at the abdominal site where fat had been harvested for a graft. Across the five largest series the range is 1.3% to 7.3%, mean 3.9% (Krengli 2016).
• The most important line for her partner's question: in the paper that pooled every published case of clival chordoma pathway seeding (Iloreta 2014), every single case followed a resection. None followed a diagnostic biopsy alone. Biopsy is listed there only as a theoretical route.
• Does having had a biopsy make the outcome worse? The MD Anderson series looked at exactly this and concluded, verbatim: "Biopsy followed by attempted radical resection at a dedicated center does not affect PFS and, therefore, represents a reasonable first step in management." (Freeman 2018.) What did make things worse in that series was an attempted operation outside a specialist centre: nearly three times the risk of progression.
• Spinal chordoma gives the same picture from a different angle. In 39 patients, the adverse factor was not biopsy but "performance of an invasive morphologic diagnostic procedure outside of the tumor center" (Bergh 2000). The consensus guidance for spinal chordoma is: do the needle biopsy with a sheathed needle, from the back, at the centre that will operate, and remove the track with the tumour (Chordoma Foundation restatement of Stacchiotti 2015; Radaelli 2020).

So chordoma does seed, more readily than most tumours, and the surgeons who treat it design their operations around that fact. That is why the biopsy route matters (through the nose, along the corridor that will be used for any later surgery, so the track is removed with the tumour), and why it should be done by the team that will do that surgery. It is not a reason to avoid tissue; it is the reason the guidelines are so specific about how tissue is obtained.

2. The parasite analogy

The thing her partner has heard about is real. It is the hydatid cyst, caused by the tapeworm Echinococcus. It is a fluid-filled sac with a living inner membrane that buds off thousands of tiny larvae (protoscolices) into the fluid. Puncturing it is dangerous for two specific reasons: the fluid is a potent allergen and can cause anaphylaxis, and every one of those larvae is an independent organism that can start a new cyst wherever it lands (Bhutani 2018; WHO-IWGE consensus, Brunetti 2010). Even so, deliberate controlled puncture is now a WHO-endorsed treatment for these cysts, with anaphylactic shock in under 0.5% (Akhan 2025).

Why this does not transfer to the patient's lesion:

• A hydatid cyst is a bag of fluid and organisms under pressure. A chordoma is the opposite. It is solid tumour tissue, lobulated, set in a jelly-like matrix, "aggressive, locally invasive" (Walcott 2012), growing through bone with no capsule. It sends microscopic tongues and satellite nodules beyond its visible edge before anyone touches it: so-called micro-skip metastases were found in 42.5% of surgical specimens (Akiyama 2018), and the surgical consensus notes "microsatellite nodules, generally below the resolution of radiological imaging" (Radaelli 2020). There is nothing sealed inside it to release.
• Fluid and solid look completely different on MRI. (This is standard radiology, stated from knowledge rather than a cited paper.) A cystic lesion is bright, uniform fluid; a solid mass enhances with contrast and, in this case, has been growing through bone. Radiologists specifically look for cystic features before anyone puts an instrument near a lesion, precisely because of hydatid. Two teams have looked at the patient's CT and MRI and called it a solid tumour. A question on the consultation sheet (Q2) asks them to confirm "solid throughout, or any cystic parts?" so the answer is in the radiologist's own words.
• Hydatid disease needs exposure (dogs and sheep in endemic regions, or travel to them); in the UK it is exceptionally rare and in the skull base rarer still. (Again, clinical knowledge, not a cited figure.)

3. "Other biological entities" inside the tumour

Chordoma is made of the patient's own cells. It grows from a leftover of the embryonic notochord, the rod that forms the spine in the embryo, and it is driven by a single well-characterised gene, brachyury (T/TBXT):

• Brachyury protein was found in all 53 chordomas tested and in none of over 300 other tumours (Vujovic 2006); it is now the standard diagnostic stain.
• Families with inherited chordoma carry an extra copy of the brachyury gene (Yang 2009); a common variant of the same gene multiplies risk sixfold (Pillay 2012).
• Whole-genome sequencing of 104 chordomas found the changes that drive it: duplications of brachyury in up to 27%, PI3K pathway mutations in 16%, and others (Tarpey 2017). All of them are alterations in human DNA.

No infectious agent, parasite or organism has ever been identified in chordoma. A search of the literature for chordoma combined with microbiome, bacteria, virus or parasite returns only papers about organisms deliberately injected as experimental treatments.

In fairness, there is a body of research claiming that bacteria live inside some human tumours (Nejman 2020, which included a general "bone tumour" group but did not identify chordoma). That work does not show that bacteria cause tumours, form part of their structure, or would be released by a needle; and the field has serious reliability problems: the most influential paper in it was retracted in 2024 for data-analysis errors (Poore 2020, retracted; Gihawi 2023). It has no bearing on the patient's decision.

4. How tumours actually spread, and what biopsy does to that

Cancers spread by invading blood vessels and lymphatics and shedding cells into the circulation. In chordoma, the features that predict a worse outcome are the tumour's own: vascular invasion and size (Akiyama 2018), and whether the surgeon achieves clear margins (Gokaslan 2016; Boriani 2006). Its distant spread, when it happens, is through the bloodstream to lungs and bone (Fagundes 1995).

The evidence that supports her partner's instinct: in mice, squeezing or biopsying a tumour can raise circulating tumour cells up to 60-fold (Juratli 2014), and core biopsy of a mouse breast tumour increased lung metastases (Mathenge 2014). Those are real findings and they are why the question is asked.

The evidence that it does not translate to people: in 55 men sampled before and after prostate biopsy, no circulating tumour cells were detectable at one week or one month (Atilla 2019). And the large human outcome studies, pancreas (2,034 patients), liver (309), breast (1,525 and 4,405), and chordoma itself (Freeman 2018), find no survival penalty from having had a biopsy. The likely explanation is the one the breast pathologists gave: displaced cells do not survive.

5. Where her partner is right

This document would be dishonest if it stopped there. The worry has a legitimate core, and here it is:

1. Chordoma seeds more readily than most tumours. The rates above (1% endoscopic, 3 to 7% open, after resection) are real, and a seeded recurrence is a serious event. It is the reason the whole speciality is careful about the route and the centre.
2. A biopsy done badly, or in the wrong place, can harm. Mankin, Bergh and Barrientos-Ruiz all found that. The Chordoma Foundation says plainly: "If not done properly, these procedures can cause the chordoma to spread." This argues for where and how, and the consultation sheet asks both (Q10 and Q11: who will do it, where, by what route, with what complication figures, and is the track inside the future resection corridor with the nasoseptal flap protected).
3. There is no published rate for seeding after biopsy alone in chordoma, because it is so rarely reported that nobody has a denominator. That cuts in her partner's favour in one sense (it is evidently very rare) and against certainty in another (the number is not zero, it is unknown and small).
4. The animal data are real. Manipulating a tumour does release cells in mice. Humans appear to clear them, but "appear to" is the honest phrase.

None of that changes the direction of the answer. Every alternative diagnosis on the patient's list is also diagnosed by biopsy, and several of them are treated without any operation at all. The only lesion class in which puncture is genuinely hazardous is a fluid-filled parasitic cyst, which the scan has already excluded. The measured risk of seeding from a properly performed endoscopic biopsy at a specialist centre is small and unquantified because it is so rare; the measured cost of operating on, or irradiating, the wrong diagnosis is not.

Sources

Chordoma seeding - Fernandes Cabral DT, Zenonos GA, Fernandez-Miranda JC, Wang EW, Gardner PA. Iatrogenic seeding of skull base chordoma following endoscopic endonasal surgery. J Neurosurg 2018;129:947. https://pubmed.ncbi.nlm.nih.gov/29271711/ - Gersey ZC et al. Techniques to reduce iatrogenic nasal seeding in endoscopic endonasal surgery for skull base chordoma. J Neurol Surg B 2026;87:e115. https://pmc.ncbi.nlm.nih.gov/articles/PMC13331662/ - Iloreta AM et al. Surgical pathway seeding of clivo-cervical chordomas. J Neurol Surg Rep 2014;75:e246. https://pmc.ncbi.nlm.nih.gov/articles/PMC4242824/ - Arnautović KI, Al-Mefty O. Surgical seeding of chordomas. J Neurosurg 2001;95:798. https://pubmed.ncbi.nlm.nih.gov/11702870/ - Krengli M et al. Tumour seeding in the surgical pathway after resection of skull base chordoma. Rep Pract Oncol Radiother 2016;21:407. https://pmc.ncbi.nlm.nih.gov/articles/PMC4899426/ - Fagundes MA et al. Radiation therapy for chordomas of the base of skull and cervical spine: patterns of failure. IJROBP 1995;33:579. https://pubmed.ncbi.nlm.nih.gov/7558946/ - Vogin G et al. Ectopic recurrent skull base and cervical chordomas, Institut Curie. Head Neck 2016;38 Suppl 1:E1238. https://pubmed.ncbi.nlm.nih.gov/26339866/ - Freeman JL et al. Impact of early access to multidisciplinary care on treatment outcomes in skull base chordoma. Acta Neurochir 2018;160:731. https://pubmed.ncbi.nlm.nih.gov/29270681/ - Bergh P et al. Prognostic factors in chordoma of the sacrum and mobile spine. Cancer 2000;88:2122. https://pubmed.ncbi.nlm.nih.gov/10813725/ - Stacchiotti S, Sommer J. Building a global consensus approach to chordoma. Lancet Oncol 2015;16:e71 (paywalled; biopsy wording taken from the Chordoma Foundation's authorised booklet). https://pubmed.ncbi.nlm.nih.gov/25638683/ and https://www.chordomafoundation.org/diagnosis/ - Radaelli S et al. The sacral chordoma margin. Eur J Surg Oncol 2020;46:1415. https://pubmed.ncbi.nlm.nih.gov/32402509/ - Gokaslan ZL et al. Mobile spine chordoma, 166 patients. J Neurosurg Spine 2016;24:644. https://pubmed.ncbi.nlm.nih.gov/26682601/ - Boriani S et al. Chordoma of the mobile spine: fifty years of experience. Spine 2006;31:493. https://pubmed.ncbi.nlm.nih.gov/16481964/

Seeding across cancers - Diaz LK, Wiley EL, Venta LA. Are malignant cells displaced by large-gauge needle core biopsy of the breast? AJR 1999;173:1303. https://pubmed.ncbi.nlm.nih.gov/10541110/ - Liebens F et al. Breast cancer seeding associated with core needle biopsies: a systematic review. Maturitas 2009;62:113. https://pubmed.ncbi.nlm.nih.gov/19167175/ - Maseki H et al. Clinical significance of tumor cell seeding associated with needle biopsy in breast cancer. Asian J Surg 2023;46:3700. https://pubmed.ncbi.nlm.nih.gov/36732183/ - Liikanen J et al. Core needle biopsy and survival in pT1 breast cancer. Eur J Surg Oncol 2016;42:64. https://pubmed.ncbi.nlm.nih.gov/26427542/ - Sennerstam RB et al. Core-needle biopsy of breast cancer and late distant metastases (counter-evidence; compares different eras). Cancer Cytopathol 2017;125:748. https://pubmed.ncbi.nlm.nih.gov/28837268/ - Silva MA et al. Needle track seeding following biopsy of liver lesions: systematic review and meta-analysis. Gut 2008;57:1592. https://pubmed.ncbi.nlm.nih.gov/18669577/ - Fuks D et al. Preoperative tumour biopsy does not affect the oncologic course of patients with transplantable HCC. J Hepatol 2014;61:589. https://pubmed.ncbi.nlm.nih.gov/24818985/ - Ayar D et al. Needle-track metastasis after transthoracic needle biopsy. J Thorac Imaging 1998;13:2. https://pubmed.ncbi.nlm.nih.gov/9440831/ - Ibukuro K et al. Needle track implantation after thoracic biopsy. AJR 2009;193:W430. https://pubmed.ncbi.nlm.nih.gov/19843723/ - Sano Y et al. CT-guided lung biopsy and pleural dissemination. Cancer 2009;115:5526. https://pubmed.ncbi.nlm.nih.gov/19685526/ - Matsuguma H et al. Pleural recurrence after needle biopsy in early lung cancer (counter-evidence). Ann Thorac Surg 2005;80:2026. https://pubmed.ncbi.nlm.nih.gov/16305838/ - Ngamruengphong S et al. Preoperative EUS-FNA does not impair survival in resected pancreatic cancer. Gut 2015;64:1105. https://pubmed.ncbi.nlm.nih.gov/25575893/ - Barrientos-Ruiz I et al. Are biopsy tracts a concern for seeding and local recurrence in sarcomas? Clin Orthop Relat Res 2017;475:511. https://pmc.ncbi.nlm.nih.gov/articles/PMC5213942/ - Mankin HJ, Mankin CJ, Simon MA. The hazards of the biopsy, revisited. J Bone Joint Surg Am 1996;78:656. https://pubmed.ncbi.nlm.nih.gov/8642021/ - Robertson EG, Baxter G. Tumour seeding following percutaneous needle biopsy: the real story! Clin Radiol 2011;66:1007. https://pubmed.ncbi.nlm.nih.gov/21784421/ - Shyamala K et al. Risk of tumor cell seeding through biopsy and aspiration cytology. J Int Soc Prev Community Dent 2014;4:5. https://pmc.ncbi.nlm.nih.gov/articles/PMC4015162/

Hydatid cyst, chordoma biology, tumour microbiome - Brunetti E, Kern P, Vuitton DA; WHO-IWGE. Expert consensus for the diagnosis and treatment of cystic and alveolar echinococcosis. Acta Trop 2010;114:1. https://pubmed.ncbi.nlm.nih.gov/19931502/ - Bhutani N, Kajal P. Hepatic echinococcosis: a review. Ann Med Surg 2018;36:99. https://pmc.ncbi.nlm.nih.gov/articles/PMC6226561/ - Akhan O, Ciftci T. Interventional radiology for liver CE and AE lesions. Visc Med 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12503702/ - Sun X, Hornicek F, Schwab JH. Chordoma: an update on the pathophysiology and molecular mechanisms. Curr Rev Musculoskelet Med 2015;8:344. https://pmc.ncbi.nlm.nih.gov/articles/PMC4630230/ - Akiyama T et al. Infiltrative features of chordoma: micro-skip metastasis. Ann Surg Oncol 2018;25:912. https://pubmed.ncbi.nlm.nih.gov/29181683/ - Walcott BP et al. Chordoma: current concepts, management, and future directions. Lancet Oncol 2012;13:e69. https://pubmed.ncbi.nlm.nih.gov/22300861/ - Vujovic S et al. Brachyury is a novel biomarker for chordomas. J Pathol 2006;209:157. https://pubmed.ncbi.nlm.nih.gov/16538613/ - Yang XR et al. T (brachyury) gene duplication confers major susceptibility to familial chordoma. Nat Genet 2009;41:1176. https://pubmed.ncbi.nlm.nih.gov/19801981/ - Pillay N et al. A common single-nucleotide variant in T is strongly associated with chordoma. Nat Genet 2012;44:1185. https://pubmed.ncbi.nlm.nih.gov/23064415/ - Tarpey PS et al. The driver landscape of sporadic chordoma. Nat Commun 2017;8:890. https://pubmed.ncbi.nlm.nih.gov/29026114/ - Nejman D et al. The human tumor microbiome. Science 2020;368:973. https://pubmed.ncbi.nlm.nih.gov/32467386/ - Gihawi A et al. Major data analysis errors invalidate cancer microbiome findings. mBio 2023;14:e0160723. https://pubmed.ncbi.nlm.nih.gov/37811944/ - Poore GD et al. Retraction note. Nature 2024;631:694. https://pubmed.ncbi.nlm.nih.gov/38926587/

Mechanism - Juratli MA et al. Real-time monitoring of circulating tumor cell release during tumor manipulation (mouse). Head Neck 2014;36:1207. https://pubmed.ncbi.nlm.nih.gov/23913663/ - Mathenge EG et al. Core needle biopsy of breast cancer tumors increases distant metastases in a mouse model. Neoplasia 2014;16:950. https://pubmed.ncbi.nlm.nih.gov/25425969/ - Atilla MK et al. Prostate biopsy and circulating tumor cells. Turk J Med Sci 2019;49:1701. https://pubmed.ncbi.nlm.nih.gov/31655516/ - Chordoma Foundation. Symptoms and diagnosis; Expert Recommendations. https://www.chordomafoundation.org/diagnosis/

Not verifiable in this review: the exact biopsy wording inside the 2015 Lancet Oncology and 2026 JAMA Oncology consensus papers (paywalled; the Chordoma Foundation's authorised summaries were used); a numeric seeding rate after percutaneous chordoma biopsy (none published); the per-site tables in Robertson and Baxter 2011.