How much 'radicular pain' can earn monthly if I develop it, exact search is 3,600 an CPC only 0,08?
And CPC for 'lung lobes' is 5,19! What about that?
CPC can be 20 for a given term, but if ads point to useless sites or ad owner runs outta money, one doesn't make any.
A site developed on radicular pain topics may show lots of pain-related ads, not necessarily radicular, which is not a commercial term, but you could get ads for "back pain" which is a common commercial term and (I guess) may pay decently.
Lung lobe means almost nothing beyond anatomical description. The CPC you report might be related to cancer lawsuits. Class actions usually make lawyers pay hefty sums for ads to lure clients into highly profitable operations, but you need a top-ten ranking for high-ad-competition terms (which is hard to get) or relevant traffic via other strategies that might be illegal under the ads provider's TOS.
How much can you earn... Only a highly developed, SEO-friendly, top-ranked, made-for-humans site can tell you the answer.