Medical Oncologist
CION Cancer Clinics
How long tissue blocks are kept, and whether an old one still works | CION Cancer Clinics
Tissue blocks from surgery and biopsies are usually kept for many years, but each hospital sets its own limit and some discard them sooner. An old block can often still be tested for an inherited gene fault, though the older it is, the more likely the test is to fail. This page explains what decides that, and how to find a relative's block before it is lost. At CION Cancer Clinics, our team helps carriers and their families plan checks, next steps and support after a genetic result.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- How long does a hospital keep a tissue block?
- What makes an old block more or less likely to work?
- How do you find out whether a relative's block still exists?
- The words you will meet, in plain language
- How does a block test compare with a blood test?
- What this page cannot tell you
- Four things families assume about old blocks
- Common questions about stored tissue blocks
The short answer
How long does a hospital keep a tissue block?
Most hospitals keep tissue blocks for many years after a biopsy or an operation, and many keep them for a decade or longer. There is no single rule that every Indian hospital follows, so the only way to know is to ask the pathology department that made the block. An old block can often still be tested for an inherited fault, but its age, how it was stored and how much tissue is left all affect the chance of success.
What a block actually is
When a surgeon removes a tumour or takes a biopsy, the tissue goes to the pathology laboratory. It is fixed in a chemical called formalin, set into a small cube of wax and sliced thinly for the microscope. The wax cube is the block. It sits in the hospital archive under a pathology number, in case the tissue is ever needed again.
Why families come looking for one
The relative who had cancer is the best person to test first. If that relative has died, their block may be the only way left to learn whether a fault runs in the family. The question usually comes up years later, when a brother, daughter or niece is sent for counselling.
Ask early. A block that exists today can be discarded in the next archive clear-out.What decides success
What makes an old block more or less likely to work?
The counsellor and the laboratory weigh four things before they agree to try.
How old the block is
DNA in a wax block slowly breaks into shorter pieces. Recent blocks usually give better results than very old ones. Some old blocks still work well, and some newer ones fail.
How it was handled and stored
Tissue left too long in formalin before processing gives more damaged DNA. Blocks kept cool and dry last better than blocks kept in a hot, damp storeroom.
Whether normal tissue is present
For an inherited question, the laboratory prefers tissue that is not tumour. A fault found only in tumour cells may have started in the tumour and may not be inherited at all.
Useful blocks often contain
- A lymph node free of cancer
- Normal tissue at the edge of the specimen
- A healthy part of the organ
How much tissue is left
A small needle biopsy may already have been used up by earlier tests. A block from a large operation usually has more to spare.
Not sure whether this applies to you?
Ask an oncologistBefore it is lost
How do you find out whether a relative's block still exists?
Find the old pathology report
Look through the relative's papers for a biopsy or histopathology report. It carries the hospital name and a pathology number, which is how the archive files the block.
Contact the pathology department directly
Ask whether the block is still held and whether normal tissue is available. The general reception rarely knows. The pathology office does.
Ask them to hold it
Request in writing that the block is not discarded while the family arranges counselling. Most departments will note this on the file.
Let the counsellor request the release
Hospitals usually release a block only to a doctor or a laboratory, with consent from the next of kin. The counsellor arranges this and tells the laboratory which block to use.
On the paperwork
The words you will meet, in plain language
- Tissue block
- A small cube of wax holding preserved tissue from a biopsy or an operation. It is the original source for any later test.
- FFPE
- Short for formalin-fixed, paraffin-embedded. It describes how almost every stored block is made.
- Pathology number
- The reference the laboratory gave the tissue. Without it, finding a block in a large archive can be very slow.
- Unstained slides
- Thin slices cut from the block onto glass. Some laboratories can work from these if the block itself cannot leave the hospital.
- Germline
- Present in every cell from birth, and therefore inheritable. This is the question a block test is trying to answer.
- DNA quality check
- A first step where the laboratory measures whether enough usable DNA can be extracted before running the full test.
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Side by side
How does a block test compare with a blood test?
Old tissue block
Fresh blood sample
DNA is often broken and may fail the quality check
DNA is intact and almost always usable
Some parts of a gene may not be read clearly
The whole panel is usually read well
Tumour faults can blur the inherited picture
Only inherited faults are present
Tissue cannot be replaced if the test fails
Another sample can simply be taken
Being straight with you
What this page cannot tell you
It cannot tell you whether a particular hospital still has your relative's block. Only that hospital's pathology department can answer that. It also cannot tell you in advance whether a block will give a usable result. The laboratory finds that out only after it has tried to extract the DNA.
It cannot read a block result for you
A result from stored tissue needs careful reading. A fault found in the block may have come from the tumour rather than from birth, and a negative result may simply mean part of the gene could not be read. What a specific result means is a question for the counsellor who ordered the test.
Who this does not apply to
Most families never need an old block. If the relative who had cancer is alive, a blood or saliva sample is simpler and more reliable. If the only cancer in the family was common and diagnosed late in life, testing a block is unlikely to change anything for the living.
Tumour testing to guide a living patient's treatment is a different question, covered under targeted therapy.Commonly believed
Four things families assume about old blocks
"The hospital will have thrown it away by now."
Often it has not. Many hospitals keep blocks far longer than families expect. It costs nothing to ask the pathology department before assuming the trail has gone cold.
"If the block is old, the test is pointless."
Age lowers the chance of success but does not rule it out. The laboratory checks the DNA first, so the family knows early whether a full test is worth running.
"Any fault found in the block must run in the family."
Tumours pick up faults of their own that were never inherited. This is why laboratories prefer normal tissue from the block, and why a counsellor confirms the finding before relatives are tested.
"The family can collect the block and take it anywhere."
Hospitals usually release blocks only to a doctor or a laboratory, with consent from the next of kin. Blocks are also fragile and must be packed properly, so the transfer is best arranged by the counsellor.
Questions we are asked
Common questions about stored tissue blocks
Is there a fixed rule on how long blocks must be kept?
Not one that every Indian hospital follows. Professional bodies recommend keeping blocks for many years, and most large hospitals do, but each institution sets its own policy. Private laboratories that closed or merged may have moved or lost their archives, so ask early.
Can a block from a very old operation still work?
Sometimes. Older blocks carry more damaged DNA, and the chance of a failed test rises with age. The laboratory runs a quality check first, so you will know whether a full test is possible before you pay for the whole analysis.
What if only the slides are left and not the block?
Stained slides kept for the microscope are harder to use, though some laboratories can extract DNA from them. Unstained slides cut from the block are more useful. Ask the pathology department exactly what they still hold.
Who has the right to ask for a deceased relative's block?
Usually the next of kin, such as a spouse or adult child, with the request routed through a doctor. Hospitals differ on the paperwork. Bring the death certificate, the pathology report and proof of your relationship when you ask.
Will testing use up the whole block?
Usually not. The laboratory needs only a few thin slices, and a large block has plenty to spare. A small biopsy block may be close to exhausted, which is one reason the counsellor asks which blocks exist before choosing one.
Does a failed block test mean there is no fault?
No. A failed test means the DNA could not be read well enough to answer the question. The family is left where it started, and the counsellor will suggest another route, such as testing a living relative who is at the closest risk.
Is the result as reliable as a blood test?
A clear pathogenic finding in normal tissue is usually reliable. A negative result from a block is less reassuring than a negative from blood, because parts of the gene may not have been read. Your counsellor will explain how much weight to give it.
Can the block be tested at a laboratory in another city?
Yes. Blocks travel by courier between hospitals and laboratories every day. The counsellor arranges the release and the packing, and the laboratory returns any unused tissue to the hospital afterwards if it is asked to.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- MedlinePlus Genetics — What is genetic testing?
- NHS — Predictive genetic tests for cancer risk genes
- Cancer Research UK — Inherited cancer genes and increased cancer risk
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Testing a deceased relative through stored tissueThe full process, once you know the block existsCan a genetic test be done from a tissue block?What the laboratory does with the blockWho should be tested first?Why the relative with cancer is the best starting pointWhat if no affected relative is alive to test?The other routes when no block can be found
Talk to us
Worried a relative's block may be discarded?
Tell us which hospital did the surgery or biopsy and roughly when. We will help you work out whether the block is worth tracing and how to ask for it. One helpline serves every CION centre.