Advances in Radiation Oncology

The main advances in radiation oncology fall into two groups. Technology now shapes the dose to the tumour and spares the organs around it: intensity-modulated and image-guided radiotherapy, tomotherapy, stereotactic radiosurgery, proton therapy and MRI-guided treatment. Dose schedules have also changed, so courses that once ran to 25 sessions can now be delivered in 15, or in selected patients in five.

Dr. Garima Singh, Principal Consultant - Radiation Oncology, BLK-Max Super Speciality Hospital, New Delhi, India, framed every one of these advances around a single trade-off. Her opening image was a person walking a tightrope stretched between two mountains, holding a balancing rod. One end of the rod is tumour control; the other is toxicity to normal tissue. Raise the dose to the tumour and toxicity rises with it. Lower the dose and toxicity falls, but so does control. The purpose of modern radiotherapy is to deliver a precisely measured dose to a defined tumour volume with minimal damage to the surrounding tissue, so that the tumour is eradicated, survival is prolonged and the patient keeps a high quality of life.

Why radiotherapy matters more as cancer incidence rises

Cancer incidence is climbing, and radiotherapy is one of the few treatments needed across almost every tumour site. Dr. Singh cited GLOBOCAN data: roughly one in five men or women will develop cancer in their lifetime, and around one in nine men and one in twelve women will die from it. In 2022 there were almost 20 million new cases and about 10 million cancer deaths worldwide. By 2040, she noted, new cases are expected to reach about 30 million a year and cancer deaths 15.3 million.

Against that burden, radiotherapy is not a niche modality. In Dr. Singh's figures, 50 to 70% of cancer patients need radiation at some point in their care. She described it as the backbone of cancer treatment.

The three intents of radiotherapy: radical, adjuvant and palliative

Radiotherapy is given with one of three intents, and the intent depends on the tumour site and stage.

• Radical (curative): radiation is the main treatment, with or without chemotherapy. Dr. Singh gave early and locally advanced head and neck cancer and locally advanced cervical cancer as examples, and noted a role for radiation in muscle-invasive bladder cancer.
• Adjuvant: radiation follows surgery to treat microscopic disease and reduce the risk of recurrence, as in breast cancer and in head and neck cancer with high-risk features.
• Palliative: in metastatic disease, radiation relieves symptoms and improves quality of life.

Site by site, the pattern she set out was consistent. In prostate cancer, early-stage disease can be treated with stereotactic body radiotherapy (SBRT) and locally advanced disease with hypofractionated radiation. Cervical cancer has a definitive role for radiation in locally advanced disease and a role in early-stage disease as well. Breast cancer uses radiation as adjuvant treatment and, in metastatic disease, as palliation. Lung, oesophageal and anal canal cancers all rely on it.

Radiation is also used for non-malignant conditions. Dr. Singh listed acoustic neuroma, fibromatosis, trigeminal neuralgia, cavernoma and cavernous haemangioma among the benign indications.

When radiotherapy is the right choice, and when it is not

The decision turns on stage. Asked by the moderator for a general rule that referring doctors could use, Dr. Singh took head and neck cancer as the worked example:

1. Early stage: surgery alone can be sufficient, but high-risk features can still call for adjuvant radiotherapy.
2. Locally advanced disease: radiotherapy is needed.
3. Stage IV disease: the role of radiotherapy is palliative. It relieves pain, bleeding, spinal cord compression or haemoptysis, with the aim of improving quality of life.

The exact timing, she stressed, is a decision for a multidisciplinary tumour board, not for a single specialist. Her centre follows international guidelines, including those of the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), for every site, and settles individual cases at tumour board. The way surgery, chemotherapy and radiation are sequenced in cervical cancer, which she used to answer a question on integrating chemotherapy, is set out in full in brachytherapy and chemoradiation for cervical cancer.

For a doctor deciding when to suspect cancer and refer, the companion series on recognising suspected cancer early covers the earlier part of the pathway.

From X-rays to linear accelerators: where radiation oncology started

Precision is a recent achievement. Between 1895 and 1900, X-rays were used for a wide range of diseases, including skin cancer and benign conditions such as eczema and lupus. The kilovoltage (orthovoltage) era followed, which allowed somewhat deeper tumours to be treated, but the dose that could safely reach a deep tumour remained limited by the skin and the tissue in the beam's path.

The megavoltage era changed that. In 1951 the first cervical cancer patient was treated with cobalt-60 at Victoria Hospital in London, Ontario. Medical linear accelerators entered clinical use in the early 1950s and became the standard platform. Most of the external beam techniques discussed in this series run on the descendants of those machines.

Types of radiation therapy: the modern toolkit at a glance

Radiation therapy has two components: external beam radiation therapy (EBRT), delivered from a machine outside the body, and brachytherapy, in which the radiation source is placed inside or next to the tumour. Dr. Singh listed the external beam techniques.

The practical effect of this progression is dose escalation. In Dr. Singh's prostate cancer illustration, which traced the field from 1935 to 2010, a dose of around 40 Gy was the practical ceiling in the early era. IMRT and IGRT made it possible to escalate to about 80 Gy while limiting the dose to the bladder and rectum, and protons and carbon ions can push the dose above 80 Gy. Higher tumour dose translates into better local control and better survival.

Hypofractionation in breast and prostate cancer: fewer sessions, same results

The second great advance is in the dose schedule itself. Dr. Singh described a move from conventional fractionation to moderate hypofractionation and now to ultra-hypofractionation.

Fractionation means splitting the total dose into daily sessions (fractions). Hypofractionation delivers a larger dose per session over fewer sessions. Breast cancer shows the shift most clearly. Early in her training, Dr. Singh gave breast cancer patients 25 fractions. After the hypofractionation trials, the standard moved to 15 fractions. After the FAST-Forward trial, five fractions can be given to selected patients.

Guidelines support the change. Dr. Singh cited UK consensus guidance, ESTRO and NCCN, and the ESTRO-ACROP 2022 consensus statement, which supports both hypofractionation and ultra-hypofractionation in breast cancer for selected candidates. Prostate cancer has followed a similar path: because prostate cancer has a low alpha/beta ratio (a measure of how sensitive a tissue is to dose per fraction), it responds well to larger doses per session, and modern precision allows hypofractionated treatment with minimal toxicity.

The patient-level consequence is substantial. Radiotherapy is non-invasive, and most patients can continue to work and carry on with daily life during treatment. In Dr. Singh's summary, the length of a radiotherapy course for breast or prostate cancer has halved over the past two decades. For an international patient, fewer sessions also means a shorter stay away from home.

Emerging advances in radiation oncology: PET-guided radiotherapy, FLASH and carbon ions

Dr. Singh closed the technology review with three directions under active investigation.

• PET-guided (biology-guided) radiotherapy: a radiolabelled tracer taken up by the tumour lets the tumour act as its own marker for targeting. Because the machine follows the tumour's own signal, the chance of missing it is lower, and the main advantage she highlighted is the ability to treat several cancer sites in one session.
• FLASH radiotherapy: delivers a very high dose rate over a very short period, with less dose to normal tissue.
• Carbon ion therapy: a heavier particle than the proton, with trials ongoing.

MRI-guided linear accelerators and proton therapy are already in clinical use and are covered in the deeper articles.

The radiotherapy access gap: treatment that patients never receive

Technology means little if patients cannot reach it. Dr. Singh cited data suggesting that at least 25% of patients who need radiotherapy do not receive it, and estimates that if every cancer patient who needed radiation had access by 2035, almost one million more lives would be saved every year worldwide. Shorter courses widen access, because each machine can treat more patients. So does precision: in Dr. Singh's example, patients whose tumours are not eligible for surgery can now be offered radiotherapy instead.

For patients travelling for treatment, the cost of radiotherapy varies with the technique and the number of sessions, which is one reason hypofractionation matters beyond the clinic.

Radiotherapy techniques explained in depth

The three deeper articles follow the structure of the masterclass.

• IMRT, IGRT and tomotherapy covers intensity modulation, image guidance, helical tomotherapy, heart sparing in left-sided breast cancer, breath-hold and motion management, MRI-guided treatment and head and neck dose constraints.
• Stereotactic radiosurgery, SBRT and proton therapy covers high-dose precision treatment of the brain and lung, its complications, proton therapy and radiotherapy for children.
• Brachytherapy and chemoradiation for cervical cancer covers intracavitary and interstitial brachytherapy and the stage-based framework for combining surgery, chemotherapy and radiation.

The questions doctors asked during the session, on stereotactic complications, paediatric cases, dose constraints and chemotherapy integration, are answered in the Live Discussion. The wider oncology specialty hub lists the other cancer series.

The thread of the masterclass leads back to her opening image. Each advance, from the multi-leaf collimator to the five-fraction schedule, moves the balancing rod: more dose where the tumour is, less where it is not, and more patients turned from cancer cases into survivors.