Does cancer in both lungs mean it has spread?

Not necessarily. Two tumours can mean one cancer that has spread to the other lung, or two separate cancers that began independently. These look very similar on a scan and are treated in opposite ways. Cancer that has spread is usually treated with drugs that work throughout the body. Two separate cancers can often each be treated on their own, with the intention of cure.

Most people are told about a second spot before anyone knows what it is. The scan report describes it, and the natural conclusion — drawn by patients, families, and sometimes by the first doctor who sees the images — is that the cancer has already travelled. That conclusion carries a great deal with it. It usually means treatment aimed at controlling the disease rather than curing it.

It is often the right conclusion. Lung cancer does spread within the lungs, and a second spot in the opposite lung is a recognised way for that to show up. But it is not the only explanation. The lungs are a large organ exposed to the same risks throughout, and it is entirely possible for two cancers to start in different places at around the same time without either having anything to do with the other. When that happens they are called synchronous primary lung cancers — two primaries, present together.

The difficulty is that a scan cannot tell you which situation you are in. Size, shape and position give hints, and an experienced radiologist will offer an opinion, but hints are not the same as an answer. The answer comes from tissue.

What is the difference, and why does it matter so much?

If one cancer has spread to the other lung, the disease is regarded as being in the bloodstream and treatment is normally with drugs given throughout the body. If there are two separate cancers, each one is staged and treated in its own right — and each may be early enough for treatment aimed at cure. The difference decides whether curative treatment is offered at all.

This is not a technical distinction. It is the difference between two quite different conversations.

Where a cancer has spread from one lung to the other, the working assumption is that cancer cells have travelled through the bloodstream, and that treating only what can be seen would leave behind what cannot. Treatment is therefore given throughout the body. It can work very well and people live for a long time on it, but it is not usually given with the expectation of cure.

Where there are two separate cancers, neither has travelled anywhere. Each is judged on its own merits: how big it is, whether it has reached any lymph glands, and whether it can be removed or treated. Two early cancers, each confined to the lung, are two curable problems occurring at the same time in the same person. Difficult, and more work than one — but a different situation entirely.

The practical consequence

A patient with two early separate cancers who is assumed to have cancer that has spread will be offered treatment aimed at control rather than cure. Nothing about the scan will ever correct that assumption. Only tissue will.

Why does each tumour need its own sample?

Because the two samples are compared with each other. Two cancers that started separately are usually different under the microscope — a different cell type, a different pattern of growth, different markers. One cancer that has spread carries the same features in both places. A sample from only one tumour cannot make that comparison.

When a pathologist examines a lung cancer, they describe far more than whether it is cancer. They record what type it is, how the cells are arranged, what patterns dominate, and how the cells look in fine detail. Additional tests can measure particular markers on the surface of the cells. Taken together this produces something close to a fingerprint.

Set two fingerprints side by side and the question usually answers itself. Two cancers that are different types — or that share a type but differ clearly in their pattern and detail — almost certainly started separately. Two that match in every respect are much more likely to be the same disease in two places.

The international staging committee that sets the rules for classifying lung cancer reached the same conclusion. Reviewing everything available, it found that only a small number of features are reliable enough to be trusted on their own: a clearly different type of cancer, matching genetic breakpoints on detailed sequencing, and a careful comparison of the two tumours under the microscope. Scan appearances and marker results are helpful pointers but can mislead when used by themselves.¹

Which is why the practical answer is usually simple: sample both.

With robotic navigational bronchoscopy. A thin flexible instrument is steered through the natural airways using a three-dimensional map built from your CT scan, allowing small tumours deep in either lung to be reached through the mouth — with no cut in the chest wall. Both lungs can be sampled in the same procedure, under one anaesthetic, usually as a day case.

Reaching two tumours in two different lungs used to be the obstacle. Needle biopsy through the chest wall is a good technique, but doing it twice on opposite sides in one sitting is not attractive, and small tumours or those sitting deep within the lung are not always reachable that way at all.

Robotic navigational bronchoscopy changed that. Your CT scan is used to build a three-dimensional map of the airways. A very fine, steerable instrument is then guided along that map, through the branching airways, out towards the tumour — and because the airways lead to every part of both lungs, the same procedure can reach a target on the left and then a target on the right without repositioning anything on the outside of the chest.

You are asleep for it. There is no incision. Most people go home the same day. Where the lymph glands in the centre of the chest also need sampling, that can usually be done in the same sitting with an ultrasound-guided camera test.

Robotic navigational bronchoscopy is the most accurate method currently available for sampling small and deeply placed lung nodules. It is not yet widely available — the platform is expensive, the training is specific, and most units in the UK do not offer it. Where it is available, it is often performed by one team and the surgery by another.

Dr Okiror performs robotic navigational bronchoscopy himself, both in his NHS practice at Guy’s and St Thomas’ and privately at London Bridge Hospital. Where an operation follows, he performs that as well. The practical effect for a patient with two tumours is continuity: the same surgeon takes the samples, sits in the meeting where the result is discussed, and carries out the treatment. Nothing has to be handed over and re-explained between the diagnosis and the operation.

More on the technique on the robotic navigational bronchoscopy page →, and on the single-anaesthetic pathway on the combined biopsy and robotic surgery page →

What other tests are needed?

A CT scan of the chest and upper abdomen, a PET-CT scan, and in most cases an MRI scan of the brain. Where the lymph glands in the centre of the chest look suspicious, or where two separate cancers are suspected, those glands are sampled directly rather than judged from the scan. Breathing tests and a general fitness assessment are done at the same time.

This part is standard. UK practice for lung cancer staging is set out in NICE guideline NG122, and any lung cancer team in the country will follow broadly the same sequence.² It is worth understanding what each test is for, because each one can change the plan.

The PET-CT looks at the whole body for anywhere else the cancer might be active. If it finds disease outside the chest, the situation is different again and curative treatment for two lung tumours is no longer the question.

The brain MRI is done because the brain is a common site for lung cancer to travel to and is not well seen on a PET scan. Committing someone to two demanding treatments only to find brain disease afterwards is exactly what this test exists to prevent.

The lymph glands in the centre of the chest matter more here than in most situations. If cancer has reached them, treatment changes substantially, and the case for two separate curative treatments weakens considerably. Scans are helpful but imperfect for this, and where there is doubt the glands are sampled directly with a camera test passed down the airway. Where two separate primary cancers are suspected, there is a strong argument for sampling rather than relying on the scan, because the consequence of getting it wrong is committing someone to two operations they should not have had.

Finally, fitness. This is assessed differently when two treatments are planned. Dr Okiror assesses it in three parts — how breathless you are, your risk from an anaesthetic and operation, and your heart. The difference here is that the question is not whether you could tolerate an operation, but whether you could tolerate the whole plan. More on fitness for lung surgery →

Can both cancers be treated?

Often, yes. Where two separate early cancers are confirmed, with no spread to the lymph glands or elsewhere, each is treated in its own right. That usually means either two operations separated by several weeks, or one operation combined with precisely targeted radiotherapy to the other tumour. Which combination is chosen depends on where each tumour sits and how much lung can safely be removed.

The plan is built around two things: the position of each tumour, and your breathing capacity. Everything else follows from those.

Where both tumours are small, in the outer parts of the lungs, and breathing capacity is good, two operations are often the cleanest answer. Each tumour is removed with the smallest amount of lung that will do the job properly — frequently a segmentectomy rather than a whole lobe — and the lymph glands are sampled at the same time, which is a diagnostic advantage surgery has over other treatments.

Where one tumour is larger or more centrally placed, or where drug treatment before surgery would help, the sequence changes. And where breathing capacity would not tolerate two operations, a combination of surgery and radiotherapy treats both while removing less lung.

Why surgery for one and radiotherapy for the other?

Two reasons, and they are separate. Position: targeted radiotherapy is safest for tumours in the outer part of the lung, and carries more risk close to the central airways and major blood vessels — so surgery generally takes the more central tumour. Breathing capacity: some people can safely lose one part of the lung but not two, and combining the treatments removes less lung overall.

This is the part of the plan that patients are least often told about, so it is worth setting out plainly.

Position. Precisely targeted radiotherapy delivers a high dose to a very small area. In the outer part of the lung, where there is little around the tumour but lung tissue, it does that job extremely well. Closer to the middle of the chest the situation changes: the main airways and the large blood vessels are there, and delivering the same dose near them carries a materially greater risk of serious complications. Radiotherapy teams have long treated the region around the central airways with particular caution for this reason.³ Surgery does not have the same constraint — a central tumour is technically more demanding to remove, but the risk profile is different in kind. So where one tumour is central and one peripheral, surgery generally takes the central one and radiotherapy the outer one.

Breathing capacity. Every lung operation removes some functioning lung. Two operations remove more than one. For someone whose breathing is already limited, two resections may be more than they can afford, even where each individual operation would be tolerable. Treating one tumour surgically and the other with radiotherapy preserves lung tissue while still treating both cancers.

Lymph glands. There is a third consideration that pulls the other way. An operation allows the lymph glands to be sampled properly at the same time, which radiotherapy does not. Where the glands are a particular question, that weighs in favour of operating on the tumour that would answer it.

How this decision is actually made

This is a judgement, taken case by case in a multidisciplinary meeting with a surgeon, a cancer specialist, a radiologist and a pathologist in the room. It is not a formula, and there is no trial that tells you the right answer for any individual patient.

What it does depend on is having both tumours characterised first. Every part of the discussion above becomes possible only once it is known that there are two separate cancers.

What if only one tumour can be sampled?

Sometimes one tumour cannot be reached safely. The usual approach is then to operate on the tumour without a diagnosis, and to treat the one already sampled with radiotherapy. Surgery both removes the tumour and provides the diagnosis, and allows the lymph glands to be sampled at the same time. Radiotherapy teams generally prefer to have a tissue diagnosis before treating.

It sounds counter-intuitive — operating on the tumour nobody has yet proved is cancer. But it follows logically. An operation is both a treatment and a biopsy. If the tumour turns out to be something else, it has still been removed and the answer has still been obtained. Radiotherapy, by contrast, treats without ever producing tissue, so a tumour treated that way without a prior diagnosis is one whose nature will never be known for certain.

Radiotherapy teams will sometimes treat without tissue where a tumour is clearly growing on repeated scans and is metabolically active on a PET scan. But given a choice about which tumour goes where, the one with a diagnosis usually goes to radiotherapy and the one without goes to surgery.

How far apart are the two treatments?

Where two operations are planned, they are usually separated by around five to eight weeks. That allows recovery from the first before the second — which matters, because the second operation is performed on someone who has recently had part of a lung removed. The interval is judged individually rather than fixed.

There are two pressures pulling in opposite directions, and the interval is where they are balanced. Waiting longer means better recovery and a safer second operation. Waiting less long means the second cancer is treated sooner. Five to eight weeks is where those two considerations usually meet, and it is enough for most people to be walking normally, off regular painkillers and back to something like their usual routine before the second admission.

It is reviewed rather than assumed. How the first recovery has gone, what the breathing tests show afterwards, what a repeat scan shows — all of it feeds into when the second treatment happens. Where the second treatment is radiotherapy rather than surgery, the interval is often shorter, because radiotherapy does not demand the same physical recovery.

Will the other cancer grow while the first is treated?

This is the worry most people have, and it is a fair one. Where drug treatment is given before surgery, it works throughout the body and therefore acts on both cancers at once, so neither is left untreated. Where the plan is surgery followed by radiotherapy, the gap is kept short and the second tumour is rescanned before its treatment.

Nobody wants to be told that one cancer is being dealt with while the other waits. It is worth knowing that the plan is designed with that specific fear in mind.

Where the larger tumour needs drug treatment before surgery — chemotherapy, often with immunotherapy — that treatment circulates throughout the body. It does not distinguish between the two tumours. So during the weeks before the operation, both cancers are receiving treatment, and the second one is not sitting untouched. This is one of the reasons that sequence is chosen when it fits.

Where the plan runs straight to surgery, the interval before the second treatment is short by design, and the second tumour is imaged again before it is treated so that nothing has changed unnoticed.

What if my breathing will only allow one operation?

That changes which combination is used rather than ending curative treatment. Lung-sparing surgery removes the tumour with a smaller piece of lung than a full lobe. Combining one operation with radiotherapy to the other tumour treats both while removing less lung. Regional lung function mapping can also show which parts of each lung are genuinely working, and sometimes gives a more favourable answer than a standard breathing test.

A standard breathing test gives one overall number for each lung. It cannot show which parts are doing the work. When lung damage is uneven — which it usually is — that single number can understate how much useful lung remains, particularly if the area being removed was contributing very little anyway. A regional functional scan maps this properly. More on borderline lung function →

Where the numbers are genuinely tight, the options are to make each operation smaller, or to make one of the treatments non-surgical. Both are used, and often together. What matters is that limited breathing capacity is a reason to plan differently, not automatically a reason to abandon treatment aimed at cure.

What does recovery involve?

Most people are in hospital for two to four days after a keyhole or robotic lung operation, and back to normal activity over four to six weeks. Where a second operation follows, that recovery period happens twice. Where the second treatment is radiotherapy, it is usually delivered over a small number of outpatient visits with far less physical impact.

The honest thing to say about two treatments is that they ask more of you than one, and that the second is harder in a way that has little to do with the operation itself. You already know what is coming. There is no unfamiliarity to carry you through it.

What helps is knowing the shape of it in advance: that the plan was made as a whole rather than one step at a time, that the interval exists to protect you rather than to delay you, and that the point of the whole exercise is treatment aimed at cure — which is not what would have been offered had the second tumour simply been counted rather than examined. More on recovery after lung surgery →

Referral notes

Situation	Suggested action
Two lung lesions, one or both unsampled, patient reasonably fit	Tissue from both before treatment intent is fixed — robotic navigational bronchoscopy can reach bilateral targets under one anaesthetic
Suspected synchronous primaries with equivocal mediastinal nodes	Direct nodal sampling rather than reliance on PET appearances
One central and one peripheral lesion	Surgical and radiotherapy opinions together — allocation depends on both position and physiology
Borderline lung function, two lesions	Regional functional imaging before concluding that only one can be treated
Patient told disease is metastatic on imaging alone	Reasonable grounds for a second opinion before palliative intent is settled
Bilateral targets, no local access to robotic navigational bronchoscopy	Both lesions can be sampled in one anaesthetic; the same surgeon performs any subsequent resection

Referrals and self-referrals are seen at London Bridge Hospital and The Lister Chelsea, usually within 2–3 working days. Imaging can be reviewed in advance of the appointment. Clinic letters are sent to GPs electronically within two working days, and within three working hours where the matter is urgent.

Sources

Detterbeck FC, Franklin WA, Nicholson AG, et al. The IASLC Lung Cancer Staging Project: background data and proposed criteria to distinguish separate primary lung cancers from metastatic foci in patients with two lung tumors. Journal of Thoracic Oncology 2016;11:651–665. PMID 26944304.
National Institute for Health and Care Excellence. Lung cancer: diagnosis and management. NICE guideline NG122.
Radiotherapy dose constraints near the central airways are long established in radiation oncology practice; the region around the proximal bronchial tree is treated with particular caution because of the risk of serious complications at high dose.

Dr Lawrence Okiror is a Consultant Thoracic and Robotic Surgeon at Guy’s and St Thomas’ NHS Foundation Trust, with private practice at London Bridge Hospital and The Lister Hospital Chelsea. He performs robotic navigational bronchoscopy and robotic lung resection, and takes referrals for patients with more than one lung tumour where the treatment intent is in question.

This page is written for patients and referring clinicians as general information. It does not replace individual assessment. Decisions about treatment for more than one lung tumour are made in a multidisciplinary team meeting following full staging.

Frequently Asked Questions

Questions About
Two Lung Cancers at the Same Time

If you have been told that cancer in both lungs means it has spread, and only one tumour has been sampled, an independent review is reasonable. Most patients are seen within 2–3 working days.

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Or call Jo Mitchelson:
020 7952 2882

Does having cancer in both lungs mean it has spread?

Not necessarily. Two tumours can mean one cancer that has spread to the other lung, or two separate cancers that started independently. These look very similar on a scan but are treated completely differently. If the cancer has spread, treatment is usually with drugs given throughout the body. If they are two separate cancers, each one can often be treated on its own with the intention of cure. The only reliable way to tell the difference is to take a sample from each tumour and compare them.

Why does each tumour need its own biopsy?

Because the samples are compared with each other. Two cancers that started separately are usually different when the pathologist examines them closely — a different cell type, a different growth pattern, different markers. One cancer that has spread carries the same features in both places. A sample from only one tumour cannot make that comparison, and without it the assumption tends to be that the cancer has spread. That assumption closes off treatment that might otherwise be possible.

How can both tumours be sampled if they are in different lungs?

With robotic navigational bronchoscopy. A thin flexible instrument is steered through the natural airways using a three-dimensional map of the chest, which allows small tumours deep in either lung to be reached and sampled through the mouth, without any cut in the chest wall. Both lungs can be sampled in the same procedure under one anaesthetic. It is the most accurate method currently available for small and deep nodules, and is not yet widely offered in the UK. Dr Okiror performs it himself at London Bridge Hospital and at Guy’s and St Thomas’, and performs the operation that follows.

Can both cancers be treated?

Often, yes. Where two separate early cancers are confirmed and there is no spread to the lymph glands in the centre of the chest or elsewhere in the body, each one can be treated in its own right. That may mean two operations, usually several weeks apart, or one operation and a course of precisely targeted radiotherapy to the other tumour. Which combination is right depends on where each tumour sits and on how much lung can safely be removed.

Why would one tumour have surgery and the other radiotherapy?

Two reasons, and they are different. The first is position. Targeted radiotherapy is safest for tumours in the outer part of the lung; close to the central airways and major blood vessels it carries more risk, so surgery is usually the better choice for a tumour in that area. The second is breathing capacity. Some people can safely have one part of the lung removed but not two. Treating one tumour with surgery and the other with radiotherapy keeps both cancers treated while removing less lung.

How far apart are the two treatments?

Where two operations are planned, they are usually separated by around five to eight weeks. That allows recovery from the first before the second, which matters because the second operation is being done on someone who has just had part of a lung removed. The interval is judged individually — how the first recovery has gone, what the scans show, and what the second operation involves.

If one cancer is being treated, will the other one grow?

This is a common and reasonable worry. Where drug treatment is given before surgery, it works throughout the body and therefore acts on both cancers at once, so neither is left untreated while the other is being dealt with. Where treatment is surgery followed by radiotherapy, the interval is kept short and the second tumour is rescanned before its treatment. The plan is made with this specific concern in mind.

What if only one of the tumours can be sampled?

Sometimes one tumour is in a position that cannot be reached safely. In that situation the usual approach is to operate on the tumour without a diagnosis and to treat the one that has already been sampled with radiotherapy. There are two reasons. Surgery both removes the tumour and provides the diagnosis at the same time, and it allows the lymph glands to be sampled during the same operation. Radiotherapy teams generally prefer to have a tissue diagnosis before treating, although they will sometimes proceed without one where a scan shows a tumour that is growing and metabolically active.

What tests are needed before treatment is decided?

A CT scan of the chest and upper abdomen, a PET-CT scan, and — depending on the stage — an MRI scan of the brain. Where the lymph glands in the centre of the chest look suspicious, or where two separate cancers are suspected, those glands are usually sampled directly with a camera test rather than judged on the scan alone. This follows standard UK practice set out in NICE guideline NG122. Breathing tests and an assessment of general fitness are done at the same time, because the plan involves treating two sites rather than one.

What if my breathing is not good enough for two operations?

That does not necessarily end curative treatment. It changes which combination is used. A smaller, lung-sparing operation such as a segmentectomy removes the tumour with a smaller piece of lung than a full lobe. Combining one operation with radiotherapy to the other tumour treats both while removing less lung overall. Regional lung function mapping can show which parts of each lung are genuinely working, and sometimes gives a more favourable answer than a standard breathing test.

Two lung cancers at the same time
Why two tumours does not always mean the cancer has spread