a rare form of cancer的用法和样例：
- It is a rare form of cancer which most often starts in the bone of pelvis or legs during teenage years.
- Only a year ago, Amber Hardin was diagnosed with a rare form of cancer that only 18 percent of children survive.
- Although DES was routinely given to prevent miscarriage, it now is known to cause a rare form of cancer in some daughters of women who took the drug.
- Mr Duff was suffering from colon and liver cancer while his wife had been suffering from a rare form of cancer known as Gist since 1992.
- This resulted in a rare form of diabetes mellitus.