FES PET for — Hormone-Receptor Breast Cancer

A standard FDG PET shows how metabolically active cells are — useful for finding tumour deposits, but unable to tell you whether those deposits are receptor-positive or receptor-negative. FES PET uses a radioactive form of oestradiol to show where oestrogen receptors are active in your body. This matters in ER-positive breast cancer because it can reveal, in a single whole-body scan, whether all your metastases are still receptor-active or whether some have changed their biology. That distinction can directly influence whether oestrogen-blocking treatment is expected to work across every site.

Not as a standard replacement. ASCO guidance is clear that tissue biopsy remains the reference standard for confirming ER status. Where FES PET adds value is in situations where biopsy is not safely possible — such as bone-only metastases that are difficult to sample — or where there are many lesions and your team needs a whole-body picture rather than a snapshot of a single site. The scan can support a clinical decision; it does not replace the pathology result that gave you your original diagnosis.

If you are responding well to current treatment and your scans are straightforward, your oncologist is unlikely to add FES PET to your plan — it is not a routine monitoring tool. It is most relevant when there is a specific question that existing tests cannot answer: for example, whether your tumour has remained receptor-active after progression, or whether all your metastases are still driven by the same biology. Raise it as a question with your team rather than requesting it directly; they will know whether it would change anything for your specific situation.

In India, diagnostic imaging agents are approved by CDSCO. [18F]-fluoroestradiol does not yet have routine CDSCO approval as a standard clinical agent. The FDA approval in 2020 applies in the USA only. A small number of Indian research institutions may be working with this tracer under research-use frameworks. If you have seen FES PET mentioned as an option for you, ask specifically which centre is offering it and under what regulatory framework they are operating.

The process is broadly similar to a standard PET-CT — you receive an injection of the tracer, rest for a period to allow it to distribute through your body, and then have the scan itself. The exact timing varies by centre and protocol. Because FES PET is not widely available in India, the preparation instructions and timing would come directly from whichever specialist centre is offering it. Ask them for a step-by-step walkthrough rather than assuming the process is identical to a scan you have had before.

It is likely to become more accessible as the technology and regulatory pathways mature, but there is no reliable timeline that can be stated now. Wider availability depends on production infrastructure for the tracer, CDSCO approval, and centres making the investment to offer it clinically. Research activity in India is growing, but 'growing research interest' and 'routine clinical availability' are meaningfully different stages. Your oncologist will be the best source of information about whether access has changed by the time it becomes relevant for you.