Are only internists able to diagnose a disease based on the patient's appearance, gait, and behaviour? There are many cases of presenting somatic diseases in the art of painting compellingly. Still, there are also paintings where the disease, and even more so the oncological one, is hidden. It may not be widely known at the time. The work aims to rehabilitate Rembrandt's Betszeba, wrongly regarded since the 1970s as an example of breast cancer, and to show Rubens's canvases, which do not hide the deformations of breast tumors. The analysis of impurities, stains and varnish deformations is becoming more and more precise thanks to modern methods of X-ray spectrophotometry. In some cases, we see that an effect once considered a disease resulted from artifacts of reconstruction or restoration of the image. Conclusions: there is strong evidence that in the case of Rembrandt's "Bethsheba in the Bath", David's wife or Henrikje Stoffels did not have breast cancer. Other paintings made by Rembrandt and Rubens illustrate a disease. It is puzzling that the artists tried to reflect the realistic nature of the human body, regardless of the existence of possible pathology.