Advance cancer cell,should be cut out with adjacent cells if it can be done.

I think this answers your concerns. If its possible you have to cut adjacent cells also. Only if cell is a advanced stage cancer.

Should I remove only next element or also previous element?

its a clever solution
as i understand you find the previous element and compare them
clever clever

what do you mean by this? url.indexOf(p1 + '=') < qPos

Why??

haha wp

If you're logging it, you don't need to return. Or just return without logging, but in the end you'll need to return a boolean.

GOT EM

"You don't need to validate the form of the Roman numeral."

"XXC" is NOT a valid roman numeral.

;))

solution("XXC") != 100

spoiler flag...

This fails the number 1990 (MCMXC) from the description.
You are missing CM, CD, XC, XL, IX, IV.