A physicist’s view of the similarities and differences between tuberculosis and cancer

In 2015 in the United States 612,000 persons died from cancer whereas only 470 died from tuberculosis (TB), a disease which was the main cause of death around 1900. How can one explain such a huge discrepancy in treatment progress? A statistical and medical comparison between TB and cancer will give some clues. What makes the question of particular interest is the fact that TB and cancer also share important features. Both TB and cancer can affect several organs, e.g. the lungs, brain, bones, intestines, skin. What in cancer is called “malignant neoplasm” (tumor) is called “granuloma” in TB. By isolating malignant cells from the rest of the body, such clusters protect the host’s organism but at the same time they are “secure beachheads” from where malignant cells can wander off to new locations. Thus, metastatic tumors have a TB parallel in the form of secondary granulomas. To investigate this parallel more closely we use the age-specific response of organs. Called spectrometric analysis in a previous paper (Berrut et al. 2017), this method provides information about how fast tumors develop and how serious they become. A characterization of the response to TB of organ j is given by the following (age-dependent) death ratio: T j ( t ) = ( death by TB of type j at age t ) ∕ ( all TB deaths at age t ) . The development of cancer tumors can be described by similar profile functions C j ( t ) . It appears that for the same organ T j ( t ) is similar in shape to C j ( t ) . In other words, the idiosyncrasies of each organ are more determinant than the functional differences between TB and cancer. Such observations bring to light vulnerabilities in the way the immune system provides protection to various organs.