Targeted radionuclide therapy in esophageal cancer

Esophageal cancer remains a serious disease in Australia, with outcomes shaped by tumour stage, biological subtype, fitness for treatment and access to specialist care. The two major forms are adenocarcinoma, often linked with Barrett’s oesophagus, and squamous cell carcinoma, which has different geographic and lifestyle patterns. Treatment commonly combines surgery, chemotherapy, radiotherapy, immunotherapy or endoscopic procedures.

Targeted radionuclide therapy is an emerging form of precision oncology. It uses a radioactive isotope attached to a molecule that recognises a feature on cancer cells. After the compound binds to its target, the isotope delivers damaging radiation close to the tumour while limiting exposure to surrounding tissue.

This approach is best understood as a developing research field for esophageal malignancies rather than an established standard of care. Its progress depends on identifying reliable tumour markers, developing suitable drug carriers and proving meaningful benefits in well-designed clinical trials. The scientific themes discussed through international forums such as the ISDE congress help place these developments in a broader clinical context.

For Australian patients, access will depend on evidence, regulatory approval, specialist nuclear medicine services and trial availability. Major centres in Melbourne, Sydney, Brisbane and Perth have experience in theranostic imaging and radionuclide treatment, while regional patients may need referral pathways involving telehealth and travel to metropolitan hospitals.

How the treatment works

A targeted radiopharmaceutical has two main components: a biological carrier and a radioactive payload. The carrier may be an antibody, antibody fragment, peptide or other molecule designed to attach to a tumour-associated protein. The payload can emit beta particles, which travel farther through tissue, or alpha particles, which deliver very high energy over a shorter distance.

Treatment often begins with molecular imaging. A diagnostic version of the compound is labelled with a scan-friendly isotope to show whether the cancer expresses enough of the target. If uptake is adequate, a therapeutic isotope may be administered. This diagnostic and treatment pairing is known as a theranostic model.

Potential targets in esophageal tumours

HER2 is one of the most established targets in esophageal and gastroesophageal junction adenocarcinoma. Some tumours produce excess HER2, allowing antibody-based medicines to bind to them. A radioactive HER2-directed agent could potentially extend the effects of targeted treatment into microscopic or resistant disease, although clinical evidence in esophageal cancer is still limited.

Other possible targets include EGFR, tissue-specific antigens and proteins associated with particular tumour subtypes. Claudin18.2 has attracted attention in upper gastrointestinal cancers, though its role varies between tumour types and individual patients. A target must be present at a sufficient level, remain accessible and ideally be expressed more strongly in cancer than in healthy organs.

Where the evidence stands

Radioligand therapy has gained clinical traction in selected neuroendocrine and prostate cancers, providing a useful proof of concept. Those successes have encouraged researchers to investigate similar strategies for gastrointestinal cancers. Esophageal tumours, however, can be biologically diverse and may show uneven target expression, creating a risk that some cancer cells receive little radiation.

Early studies generally focus on safety, distribution through the body, radiation dose and signs of anti-tumour activity. Later trials must establish whether the therapy improves progression-free survival, overall survival or quality of life compared with current treatment. A reduction in scan size alone is insufficient if treatment causes substantial toxicity or fails to delay symptoms.

Safety and treatment planning

The main concerns depend on both the carrier and the isotope. Radiation may affect bone marrow, kidneys, liver or other organs, while antibodies can produce infusion reactions. Alpha-emitting agents may be powerful against small clusters of cancer cells but require careful control of exposure and long-term monitoring.

Patients usually undergo blood tests, kidney and liver assessment, imaging and review of previous therapies. Radiation precautions after treatment vary according to the isotope and dose. Australian nuclear medicine departments follow local radiation-safety requirements, and treatment may involve a dedicated inpatient room or carefully managed outpatient instructions.

Australian research and access

Australia has strong capabilities in cancer imaging, nuclear medicine and early-phase clinical research. Institutions such as Peter MacCallum Cancer Centre in Melbourne, Royal North Shore Hospital in Sydney and major university-linked hospitals contribute to specialist oncology research. Availability is uneven, however, and a trial in Melbourne or Sydney may require substantial travel from Adelaide, Hobart, Darwin or rural New South Wales.

The Therapeutic Goods Administration evaluates medicines for the Australian market, while research studies may be listed through the Australian New Zealand Clinical Trials Registry. Public hospital funding, private insurance and trial sponsorship can affect practical access. Patients should receive advice from a multidisciplinary team rather than assuming that an overseas radionuclide treatment is suitable or approved locally.

The role of testing and personalised care

Targeted radionuclide treatment is most promising when therapy is matched to a demonstrated tumour feature. Biopsy-based testing can assess markers such as HER2, while imaging may reveal whether the target is present throughout the body. This distinction matters because a marker found in the original tumour may be weaker or absent in later metastases.

Treatment decisions also need to account for swallowing symptoms, nutrition, previous radiotherapy, kidney function and the location of disease. Dietitians, radiation oncologists, medical oncologists, surgeons, pathologists and nuclear medicine specialists may all contribute. In Australia, coordinated care is especially important when a patient moves between a local health service and a metropolitan cancer centre.

The field is moving towards more selective radiation delivery, better patient selection and combinations with chemotherapy, immunotherapy or other targeted medicines. Its future will depend on evidence that translates laboratory precision into longer survival and better daily function. The key point to remember is that targeted radionuclide therapy is a promising, carefully developing option for selected esophageal cancers, not yet a universal replacement for established treatment.