My mum has been told she has shadows on her liver & pancreas. Does this have to mean cancer?

'Shadows' is vague at best. When I take and read x-rays of my patients (I'm a chiropractor) sometimes there are unknown densities or lucencies (one darkens a picture and the other lightens a picture). These terms are more accurate than shadows. Some of the things that cause imaging 'unknowns' can be a cyst (benign), gas (which can shadow or darken an image), an imaging artefact (error) can be due to patient motion during picture taking. Magnification and distortion with patient positioning may also produce errors and artefacts.