The word "many" was in my post.

For my sins I'm a doctor, and the epidemiology of oncology is my specialist field, although other aspects of public health pay the bills at present. Cancerous cells can be and are obstructive, hence their primary status. Sadly my work with Imperial Health on mortality rates shows pulmonary obstruction as the "mercy shot" even in many leukaemic cases. The word "healthy" is one I'd probably not use in context in your post.

Funnily enough, I naturally presumed my less scientific claim on western lifestyle might have provoked debate rather than the established statement on pneumonia?

Ah well.