Written in blood

摘要

Casey lim~* was 11 weeks pregnant when she gave a blood sample to test for Down's syndrome. It revealed multiple abnormalities in fragments of DNA circulating in her blood. Further analysis showed that the mutant DNA wasn't from the fetus but from Lim's own white blood cells. A form of blood cancer called follicular lymphoma, which she had battled two-and-a-half years earlier, had stealthily returned. Lim was one of the lucky ones. All too often, cancers are caught only after they have spread and mutated into subtly different forms. This ability to evolve and resist our best treatments is what makes cancer such a formidable foe. One way to root out its weaknesses is to repeatedly remove chunks of tumour for analysis, but that is invasive and often risky.