In cancer care, PET (usually PET-CT) is used at several points: to help stage a cancer at diagnosis, to check whether treatment is working, and to look for recurrence in follow-up. The findings feed into decisions made by a multidisciplinary team, alongside examinations, blood tests, biopsies and other scans. PET is one important input — not the whole picture — and how often it's used depends on the cancer and the decisions that hinge on the result.
Key takeaways
- PET informs cancer decisions at diagnosis, during treatment and in follow-up.
- It helps stage cancer, assess treatment response and detect recurrence.
- Findings feed into a multidisciplinary team's decisions, with other tests.
- It's one important input, not the whole picture.
In cancer care, a PET scan is rarely a one-off — it’s an input your treating team uses at several points along the journey.[1]
Where PET fits
- At diagnosis — to help stage the cancer (work out its extent and whether it has spread), which shapes the whole treatment plan.[2]
- During treatment — to check whether the cancer is responding, so treatment can be continued or changed.
- In follow-up — to look for recurrence if symptoms or other tests raise a concern.
Because many cancers are very active, PET (usually as a PET-CT) can add information that structural scans alone can’t.[1]
One input among several
In Australia, most cancer care is coordinated through a multidisciplinary team — surgeons, oncologists, radiologists, nuclear medicine specialists and others — who review your results together.[2] PET findings are interpreted by a specialist and weighed alongside examinations, blood tests, biopsies and other imaging. An active spot on PET is a clue considered in context, not a standalone verdict.
The radiation dose of a PET-CT (around 14 mSv) is balanced against how much the information will actually change your care — a scan that won’t alter the plan usually isn’t done.
Frequently asked questions
How often will I need a PET scan during cancer treatment?
It varies — some people have one at diagnosis and a follow-up to check response; others have more. Your team decides based on the cancer type and how much a decision depends on the result.[1]
Who decides what my PET results mean for treatment?
A specialist interprets the scan, but treatment decisions are usually made by your multidisciplinary team, combining the PET with your other tests and your preferences.[2]
Sources
- RadiologyInfo.org (RSNA & ACR) — General Nuclear Medicine (PET) — www.radiologyinfo.org/en/info/gennuclear
- Cancer Council Australia — Tests for cancer — www.cancer.org.au/cancer-information/what-is-cancer/tests-for-cancer
- RANZCR / InsideRadiology — Nuclear medicine (Cain) — www.insideradiology.com.au/nuclear-medicine/
