* Lung: PET scans are just as accurate as biopsies, with no significant health risks (Appl Radiol, 2003; 32: 9-17).

* Breast: MRI has variable accuracy (60-100 per cent) (Acad Radiol, 1999; 6: 387-97). PET scans are more reliable (90 per cent accuracy), but are still in the developmental stage (Recent Results Cancer Res, 2000; 157: 12-9). Another promising technique on the near horizon is MRSI, which can detect choline, a marker for breast cancer. Thermography (heat measurement) is a safe early-warning device, but cannot give a definitive diagnosis of cancer.

* Liver: CT and ultrasound scans are nearly 100 per cent accurate, leading some experts to conclude that biopsy is no longer worth the risks (Liver Transpl, 2004; 10 [2 Suppl 1]: S30-3). A simple blood test can also detect cancer in some cases.

* Prostate: endorectal MR (magnetic resonance) is claimed to be the most accurate imaging technique. It is not very good at detecting microscopic disease, but this may be unimportant in prostate cancer (Magn Reson Imaging Clin N Am, 2000; 8: 869-86).

* Pancreas: endoscopic ultrasound (EUS) is 90 per cent accurate and now considered the ‘gold standard’ for cancer detection (Ann Oncol, 1999; 10 [Suppl 4]: 25-7). Helical computed tomography (HCT) is 95-100 per cent accurate, but may not be suitable for all patients (Dig Dis, 2001; 19: 37-46).

* Womb: endovaginal ultrasound (EVUS), a specialised form of ultrasound, is 96 per cent accurate in diagnosing cancer, and is painless and non-invasive (JAMA, 1998; 280: 1510-7).

* Colon: CT scans are routinely used to detect colorectal cancer, but have some limitations. PET scans are more accurate and are becoming more widely available (Q J Nucl Med, 2001; 45: 215-30).

* Bone: MRI is routinely used as an alternative to bone biopsy, and is almost as accurate.