The Collaborative International Dictionary of English v.0.48:

Cankerous \Can"ker*ous\, a.
   Affecting like a canker. "Canrerous shackles." --Thomson.
   [1913 Webster]

         Misdeem it not a cankerous change.       --Wordsworth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cankerous
    adj 1: having an ulcer or canker [syn: cankerous, ulcerated,
           ulcerous]