He has since had a successful operation to remove it, and has been undergoing chemotherapy that was expected to last a few months.
Lady Dianne said: "As with the first statement released on this matter, we disclose these details solely in the interests of transparency, and to avoid speculation and gossip.
"We would again ask that people respect our request for privacy."
Hadlee's cricketing greatness is easily defined. He secured a world record 431 test wickets by retirement, had been the lynchpin in New Zealand's golden era of the 1980s and brandished a knighthood in his final test.
Few players in the history of the game have carried as much responsibility within an international team.
Hadlee's 17-year test career saw him become the world test wicket record holder against India at Bangalore in 1988. He overtook Sir Ian Botham's 373-wicket mark when Chris Kuggeleijn caught India's Arun Lal in the slips. Hadlee took a wicket with his final ball in a test against England at Edgbaston in 1990 where he was listed on the scorecard as 'Sir Richard'.
His bowling average of 22.29 from 86 tests is among the best in the game. That statistic was complemented by the all-rounder tag, courtesy of 3124 test runs and 27.16.
Hadlee dealt with life in the limelight as much as any New Zealand sportsperson ever has during his playing career. He received the supreme Halberg award twice and was honoured as the sportsperson of the 1980s.