Small Cell Lung Cancer: How It Starts, Who Is at Risk and Signs to Watch

Why Small Cell Lung Cancer Is Different From Other Lung Cancers

Written By: Nitin Goswami, Senior Medical Content Writer  |  Medically Reviewed By: Dr. Chirag C Shah, MBBS

If someone close to you has just been told they have "small cell" lung cancer, you've probably noticed that doctors talk about it differently. There's more urgency. Treatment starts quickly. That's because this isn't the same illness as the more common kind of lung cancer, even though both start in the lungs.

This article is about the part most people want to understand first: how does this cancer actually start, who gets it, and what can you do to protect yourself or catch it early? We'll also cover what the numbers look like in India, and where treatment stands today.

Small Cell Lung Cancer at a Glance

How Does Small Cell Lung Cancer Start?

Every cancer begins with damage to a cell's DNA. Normally your body repairs that damage or gets rid of the faulty cell. Cancer starts when the damage hits the genes that act as the cell's brakes, and the cell keeps dividing when it should stop.

In small cell lung cancer, two of those brake genes are almost always switched off: TP53 and RB1. A 2021 review in Nature Reviews Disease Primers found these tumours also carry a very high number of mutations. That's the fingerprint of years of exposure to the chemicals in tobacco smoke, which keep damaging the cells lining your airways, puff after puff.

Here's the bit that makes SCLC so dangerous. The cells divide unusually fast and they spread early, often to the lymph nodes in the chest, the brain, the liver and the bones. According to that same review, most patients already have cancer that has spread by the time they're diagnosed. Only about one in three is caught at an earlier stage where treatment aimed at cure is possible.

If you'd like a simpler, broader explanation of how cancers grow, our beginner's guide to cancer is a good place to start.

Small Cell vs Non-Small Cell: What's the Real Difference?

The names come from how the cells look under a microscope, but the difference matters well beyond the lab:

• How common: about 13% of lung cancers are small cell and about 77% are non-small cell, according to the American Cancer Society.
• Speed: small cell grows and spreads faster.
• Link to smoking: both are linked to tobacco, but small cell is especially tied to it. A Spanish study of never-smokers describes SCLC as "infrequent" in people who've never smoked.
• Gene tests: non-small cell cancers are often tested for targetable changes like EGFR. If that's the kind your family is dealing with, our article on treating EGFR-positive lung cancer covers it.
• Staging: small cell is usually staged in just two groups, limited and extensive.

Who Is Most at Risk?

A risk factor doesn't mean you'll definitely get cancer. Plenty of people with several risk factors never do, and a few people with none still get it. But some things clearly raise the odds, and the good news is that the biggest ones are things you can change.

Risks You Can Do Something About

1. Smoking, in Any Form

This is the big one. The National Cancer Institute says the earlier you start, the more often you smoke and the more years you keep at it, the higher your risk climbs. Pipes and cigars count too.

What About Bidis?

A lot of people in India believe a bidi is "lighter" than a cigarette because it's small and made of leaf. It isn't safer. It's still burnt tobacco, and you're still breathing the smoke deep into your lungs. In India, bidis are actually smoked by more people than cigarettes. Look at the numbers from the government's Global Adult Tobacco Survey (GATS-2, 2016-17):

Notice how the gap between men and women lines up with the AIIMS finding that 86.4% of SCLC patients there were men.

2. Other People's Smoke

You don't have to smoke to breathe it in. The American Cancer Society calls secondhand smoke the third most common cause of lung cancer in the United States. In India, GATS-2 found that 38.7% of adults are exposed to tobacco smoke at home and 30.2% at work. If you live with a smoker, asking them to smoke outside isn't fussy, it's protecting your lungs.

3. Smoke From the Kitchen Fire

The World Health Organization says around 2.1 billion people still cook on open fires or simple stoves burning wood, dung, crop waste, coal or kerosene. WHO lists lung cancer among the diseases this household smoke leads to, and it hits women and children hardest because they spend the most time near the stove. Switching to LPG, electricity or biogas, or at least keeping the kitchen well ventilated, really does help.

4. Dust and Chemicals at Work

Some jobs expose you to substances that damage the lungs over time. The ones named by the American Cancer Society and the National Cancer Institute include:

• Asbestos (old insulation, shipyards, mines, demolition work)
• Silica dust
• Arsenic, chromium, nickel, cadmium and beryllium
• Soot, tar and coal products
• Radioactive ores such as uranium

The ACS notes that asbestos workers who also smoke have a much greater risk. If you work around any of these, wear the protective mask properly, every shift.

5. Radon Gas

Radon is a radioactive gas from soil and rock that you can't see or smell. The U.S. EPA ranks it as the second-leading cause of lung cancer in America and the top cause among people who don't smoke. It builds up indoors, particularly in basements.

6. Beta-Carotene Pills if You Smoke

This one surprises people. Several studies found that smokers who took beta-carotene supplements actually had a higher risk of lung cancer, so the ACS advises against them. Getting nutrients from fruit and vegetables is a different matter and may help a little.

Risks You Can't Change

• Age: most people diagnosed with lung cancer in the U.S. are 65 or older, and the average age is about 70. In the AIIMS study the average was younger, at 57.3.
• Family history: if your parent, brother or sister had lung cancer, your own risk may be slightly higher, especially if they were diagnosed young. The ACS says it isn't clear how much of that is shared genes and how much is a shared smoky home.
• Past chest radiation: for example, treatment for Hodgkin lymphoma or breast cancer.
• Outdoor air pollution: it raises risk slightly. The ACS puts it far below smoking.
• HIV infection is also listed by the National Cancer Institute.

How Many People Does It Affect?

Lung cancer as a whole is now the world's most common cancer and its biggest cancer killer. Here's what GLOBOCAN 2024, the World Health Organization's cancer estimates, shows:

• Worldwide: 2,637,005 new lung cancer cases and 1,861,839 deaths in 2024, ranking first for both.
• Asia's share: 65.6% of the world's new cases.
• India: 112,659 new cases (3rd most common cancer) and 98,687 deaths in 2024.
• Indian men: lung cancer is the 2nd most common cancer, with 79,048 new cases.
• United States: the American Cancer Society expects about 229,410 new cases and 124,990 deaths in 2026.

That India figure is the one that stops people. More Indians die of lung cancer than of any other cancer, breast and mouth cancer included:

Early Signs You Shouldn't Brush Off

Most lung cancers don't cause symptoms until they've spread. That's exactly why it's worth knowing the early ones. See a doctor if you notice:

• A cough that doesn't go away, or gets worse
• Coughing up blood or rust-coloured phlegm
• Chest pain that's worse when you breathe deeply, cough or laugh
• Breathlessness, or new wheezing
• A hoarse voice
• Losing weight or appetite without trying
• Feeling unusually tired or weak
• Chest infections like bronchitis or pneumonia that keep coming back
• Swelling in the face and the veins of the neck

Signs That It May Have Spread

• Bone pain, often in the back or hips
• Headaches, weakness or numbness in an arm or leg, dizziness, balance trouble or seizures
• Yellowing of the skin or eyes
• Lumps in the neck or above the collarbone

Strange Symptoms That Don't Seem to Be About the Lungs

Small cell tumours sometimes release hormone-like substances or trigger the immune system to attack nerves. Doctors call these paraneoplastic syndromes, and the ACS says they're more often linked to small cell lung cancer. Because the symptoms show up somewhere else in the body, another illness may get blamed first. If a smoker develops odd hormone or nerve problems with no clear cause, it's fair to ask whether the lungs have been checked.

Why Delays Happen in India

In the AIIMS New Delhi study, the median time from first symptom to a confirmed diagnosis was 91 days, about three months. A lingering cough is easy to treat as "just a cough" or put down to pollution. If you smoke or used to, and a cough or breathlessness lasts more than a few weeks, ask for a chest X-ray or CT scan instead of another round of cough syrup.

How Doctors Confirm It and Stage It

Your doctor will usually start with a chest X-ray and a CT scan. A sputum test can look for cancer cells in the phlegm you cough up. The diagnosis is confirmed with a biopsy, where a small piece of tissue is checked under a microscope.

Once it's confirmed, more scans show how far it has spread. The National Cancer Institute describes two stages:

• Limited stage: the cancer is in one lung and may have reached the area between the lungs or the lymph nodes above the collarbone.
• Extensive stage: it has spread beyond that, to other parts of the body.

What Survival Looks Like by Stage

These are U.S. five-year relative survival figures from the National Cancer Institute's SEER database, published by the American Cancer Society. They reflect people diagnosed between 2012 and 2018, before some of today's newer treatments were available, so they're a starting point rather than a prediction for any one person:

Look at the drop from 34% to 4%. Finding it before it spreads makes a huge difference, and that's the whole reason the early signs above matter.

What You Can Do Starting Today

To Lower Your Risk

• Quit tobacco, all of it. The ACS says damaged lung tissue slowly starts to repair once you stop, and quitting lowers your risk at any age.
• Make your home smoke-free, for your family's sake as much as yours.
• Cook with cleaner fuel or improve kitchen ventilation.
• Use proper protection at work if you handle dust, asbestos or chemicals.
• Eat plenty of fruit and vegetables, and skip beta-carotene pills if you smoke.

Should You Get Screened?

In the U.S., the Preventive Services Task Force recommends a yearly low-dose CT scan for adults aged 50 to 80 who have a 20 pack-year smoking history and still smoke or quit within the past 15 years. (A pack-year means smoking one pack a day for a year.) India doesn't have a national lung screening programme, so if you fit that description, talk to a chest physician about whether a scan makes sense for you.

How Is It Treated Today?

Because it spreads early, SCLC is mostly treated with medicines that work throughout the body, and several of them appear in our list of cancer medicines. Your oncologist will decide the exact plan. Here's how it usually looks, according to the American Cancer Society:

Limited Stage

• Chemo plus chest radiation at the same time (concurrent chemoradiation) is the standard for most people in good health. The chemo is usually etoposide with cisplatin or carboplatin.
• Durvalumab (Imfinzi), an immunotherapy, may follow if the cancer hasn't worsened after chemoradiation.
• Surgery is only an option for very few people, those with one small tumour and no spread to the lymph nodes.
• Preventive brain radiation (PCI) may be offered. The ACS notes that without prevention, about half of people with SCLC have cancer spread to the brain.

Extensive Stage

• Chemo plus immunotherapy is the usual first treatment: etoposide with cisplatin or carboplatin, together with atezolizumab (Tecentriq) or durvalumab (Imfinzi).
• Maintenance: the immunotherapy can then continue on its own, with or without lurbinectedin (Zepzelca).

Newer Options for Maintenance and When Cancer Returns

Tarlatamab (Imdelltra)

Tarlatamab is a newer kind of immunotherapy that latches onto a protein called DLL3 on the cancer cells and pulls the body's own T-cells in to attack them. It's approved by the U.S. FDA for adults with extensive-stage SCLC that has grown during or after platinum chemotherapy.

In the DeLLphi-304 trial (New England Journal of Medicine, 2025), 509 patients were split between tarlatamab and standard chemotherapy. People on tarlatamab lived a median of 13.6 months, compared with 8.3 months on chemotherapy. Fewer had severe (grade 3 or higher) side effects (54% vs 80%), and fewer stopped treatment because of them (5% vs 12%).

What to Be Ready For

The label carries a boxed warning for cytokine release syndrome (a strong immune reaction causing fever, low blood pressure and breathlessness) and for nerve-related side effects. To lower that risk, the first doses are stepped up gradually and patients are monitored for 6 to 8 hours after the first two doses. If your doctor has suggested it, here's how patients get Imdelltra in India through our program.

Lurbinectedin (Zepzelca)

According to its current U.S. label, lurbinectedin is used together with atezolizumab as maintenance treatment for extensive-stage SCLC that hasn't grown after first-line treatment with atezolizumab, carboplatin and etoposide. The idea is to hold the cancer back for longer after that first round.

Getting Newer SCLC Medicines in India

Some of these newer medicines may not be sold in India yet. A Named Patient Program lets a patient legally import a medicine approved abroad, on their doctor's prescription, with the import documents in order. We handle the paperwork, sourcing and cold-chain delivery so your family can focus on care.

If your oncologist has suggested tarlatamab or lurbinectedin, talk to our patient access team and we'll walk you through what's needed.

Questions People Often Ask

Can you get small cell lung cancer if you've never smoked?

Yes, but it's uncommon. Researchers describe SCLC as infrequent in never-smokers. Secondhand smoke, radon, workplace exposures and cooking smoke are among the other known risks.

Is a bidi safer than a cigarette?

No. A bidi still burns tobacco and you inhale the smoke. There's no safe form of smoked tobacco.

Does quitting help if I've smoked for 20 or 30 years?

Yes. The American Cancer Society says that whatever your age or how long you've smoked, quitting lowers your lung cancer risk and helps you live longer.

Why is small cell lung cancer usually found late?

It grows and spreads quickly, and early symptoms like cough and tiredness are easy to mistake for something minor. Most patients already have spread at diagnosis.

What is the survival rate for small cell lung cancer?

In U.S. SEER data, five-year relative survival is 34% when it's still localized, 20% when it's regional, 4% when it's distant and 9% overall. Newer treatments approved since then aren't reflected in those numbers.

Is small cell lung cancer hereditary?

Not in the usual sense. Most cases come from DNA damage built up over a lifetime, mainly from tobacco. Having a close relative with lung cancer does raise your risk, though.

Why get these medicines through Named Patient Program instead of any online seller?

Because you can't tell a fake or badly stored cancer medicine by looking at it. Unregulated sellers can pass on counterfeit, expired or heat-damaged stock. We source directly from authorised manufacturer networks, with full import documentation and batch traceability, and temperature-controlled delivery, so you know exactly what you're getting.

Is Imdelltra available in India?

Patients in India can get it through a Named Patient Program, which means a legal, documented import on your oncologist's prescription. Imdelltra is approved by the U.S. FDA and was authorised in the European Union on 29 May 2026 under the name Imdylltra. Our page on Imdelltra price in India covers cost, paperwork and delivery.

This article is for general information and doesn't replace advice from your own doctor. Named Patient Program doesn't prescribe medicines; we help patients access them legally once a doctor has prescribed them.

References

1. American Cancer Society: Key Statistics for Lung Cancer
2. American Cancer Society: Lung Cancer Risk Factors
3. American Cancer Society: Can Lung Cancer Be Prevented?
4. American Cancer Society: Signs and Symptoms of Lung Cancer
5. American Cancer Society: Lung Cancer Survival Rates (SEER)
6. National Cancer Institute: Small Cell Lung Cancer Treatment (PDQ), Patient Version
7. Rudin CM et al. Small-cell lung cancer. Nature Reviews Disease Primers, 2021; 7(1):3
8. Iyer H et al. Clinical profile of small-cell lung cancer in North India: a 12-year analysis (AIIMS New Delhi). Lung India, 2022; 39(6):495-501
9. Torres-Durán M et al. Small-cell lung cancer in never-smokers. ESMO Open, 2021; 6(2):100059
10. GLOBOCAN 2024: India Fact Sheet (IARC/WHO)
11. GLOBOCAN 2024: Lung Cancer Fact Sheet (IARC/WHO)
12. Global Adult Tobacco Survey 2, India 2016-17 Fact Sheet (Ministry of Health and Family Welfare)
13. World Health Organization: Household Air Pollution and Health
14. U.S. Preventive Services Task Force: Lung Cancer Screening Recommendation
15. Mountzios G et al. Tarlatamab in Small-Cell Lung Cancer after Platinum-Based Chemotherapy (DeLLphi-304). New England Journal of Medicine, 2025; 393(4):349-361
16. DailyMed: Imdelltra (tarlatamab-dlle) Prescribing Information
17. European Medicines Agency: Imdylltra (tarlatamab) EPAR
18. DailyMed: Zepzelca (lurbinectedin) Prescribing Information