Radiation Therapy for Lung Cancer — SBRT & IMRT Explained

Stereotactic body radiation therapy (SBRT), also called SABR, is a precise radiation treatment for early-stage lung cancer in patients who cannot have surgery. It delivers highly focused, high-dose radiation beams from multiple angles that all converge on the tumour, so the surrounding healthy lung receives a much lower dose. Treatment is completed in just 3 to 5 sessions over 1 to 2 weeks, as an outpatient, with no anaesthesia or hospital admission. For appropriately selected early-stage tumours, local control rates with SBRT are around 85 to 95% at three years — comparable to surgery.

SBRT and IMRT are both forms of precise external-beam radiotherapy, but they are used for different situations. SBRT delivers a very high dose to a small early-stage tumour in just 3 to 5 sessions, with curative intent when surgery is not possible. IMRT (intensity-modulated radiotherapy) shapes the dose to match larger or more complex tumours and is usually given over about 6 weeks, most often combined with chemotherapy for locally advanced (Stage III) NSCLC. In short: SBRT is for small early tumours over a short course; IMRT is for larger, locally advanced disease over a longer course. Your radiation oncologist selects the technique based on tumour size, location, and stage.

Radiotherapy is used instead of surgery when an operation is too risky or not possible — for example, when a patient has significant heart or lung disease, is frail or elderly, has other serious medical conditions, or chooses not to have surgery. For early-stage lung cancer in these situations, SBRT is the main curative-intent alternative and can achieve outcomes approaching surgery for small tumours. Radiotherapy is also the primary treatment (with chemotherapy) for Stage III locally advanced disease that cannot be removed by surgery. If you have been told you are not fit for surgery, it is worth asking a radiation oncologist whether SBRT is an option.

It depends on the type. SBRT for early-stage lung cancer is usually completed in just 3 to 5 sessions over 1 to 2 weeks. IMRT for locally advanced NSCLC, given with chemotherapy, is typically delivered daily (5 days a week) over about 6 weeks — roughly 30 sessions. Palliative radiation to relieve symptoms is often much shorter, sometimes a single session. Your radiation oncologist will confirm the exact number of sessions in your plan, as it is individualised to your tumour, stage, and lung function.

The radiation beam itself is painless — you feel nothing while it is delivered, and you do not become radioactive. Most patients can drive themselves home afterwards. Any discomfort comes from side-effects that may build up over a course of treatment, such as tiredness, mild skin changes over the treated area, or soreness on swallowing if the food pipe is near the treatment field. These are usually temporary and manageable, and your team supports you throughout. SBRT, because it treats a small area in a few sessions, is generally very well tolerated.

The most common side-effect is tiredness, which builds up during treatment and eases over the following weeks. Other effects depend on the area treated and may include soreness on swallowing (oesophagitis), a temporary worsening of cough or breathlessness, and mild skin changes like redness or dryness over the treated area. A small number of patients develop radiation pneumonitis (lung inflammation), which is treated with steroids. Radiotherapy does not cause whole-body hair loss — only hair in the treated area may be affected. Side-effects are usually milder with modern image-guided techniques that spare healthy tissue. Tell your team early about any new or worsening symptom.

Radiotherapy can be curative for some lung cancers. For early-stage disease in patients who cannot have surgery, SBRT is given with curative intent and achieves local control comparable to surgery in appropriately selected tumours. For Stage III locally advanced NSCLC, concurrent chemoradiation followed by consolidation immunotherapy can cure a meaningful proportion of patients. For Stage IV (advanced) disease, radiotherapy is usually used to relieve symptoms rather than to cure. Whether cure is the goal depends on the stage and type of cancer, which is why every case is reviewed by a multidisciplinary tumour board before treatment begins.

Concurrent chemoradiation means radiation and chemotherapy are given at the same time, rather than one after the other. For Stage III locally advanced NSCLC, this combination is more effective than either treatment alone, partly because chemotherapy makes cancer cells more sensitive to radiation. Radiation is usually delivered over about 6 weeks (5 days a week), with chemotherapy infusions at intervals during the course. Eligible patients whose disease has not progressed then receive up to a year of consolidation immunotherapy (durvalumab) to maintain long-term control. The radiation oncologist and medical oncologist plan the sequence together.

Yes. In limited-stage small cell lung cancer — where the disease is confined to one side of the chest — radiation to the chest is combined with chemotherapy and is an important part of curative treatment. Good responders may also be offered prophylactic cranial irradiation (PCI), a low dose of radiation to the whole brain that reduces the risk of the cancer spreading there, a common pattern in SCLC. In extensive-stage SCLC, radiation is mainly used to relieve symptoms or, in selected cases, to consolidate a good response to chemotherapy and immunotherapy.

Costs vary with the technique, the number of sessions, and whether chemotherapy is given alongside. As a general guide, a full SBRT course of 3 to 5 sessions is in the region of ₹1,20,000–₹2,50,000, while a full IMRT course over about 6 weeks may range higher depending on technique and fractions. Concurrent chemoradiation for Stage III, which includes both radiation and chemotherapy infusions, is more involved. A personalised estimate is provided after your initial CION consultation, and EMI options and cashless empanelment with major TPAs are available. Please confirm current figures directly with the team.

Absolutely. A second opinion is particularly valuable for radiotherapy in two situations: if you have been told you cannot have surgery but no one has discussed whether SBRT could be a curative alternative; and if you are unsure whether the radiation type, dose, or schedule proposed is right for your stage. CION offers a dedicated second-opinion service in which a radiation oncologist reviews your scans and plan alongside the wider tumour board, and explains your options clearly. It is free for cancer patients and carries no obligation to start treatment with us.