They all have blogs on Yahoo's Health Web site.
"Testicular cancer strikes mostly young men, rarely women. Simply because women of course do not have testicles. (And thank heavens for that)," writes comedian Tom Green, who survived testicular cancer.
"If you feel any sort of pain, numbness, or whatever in your er...private area...just go to a doctor," Green writes. "If you think that something is wrong, don't be embarrassed. Just go to the doctor right away. It could save your life. It saved mine."
The blogs, which will be updated about every week, are part of a monthlong campaign called "Blog for Hope." The sites provide a link for donating to the American Cancer Society. The celebrity blog feature is part of a new Health Blogs section, which includes blogs by experts on a variety of topics, including nutrition, asthma, allergies, yoga, depression and sex.
In their blogs, most of the celebrities write about their personal experiences with cancer.
"This may sound strange, but there was something good about having cancer. I got to know myself better," writes Fleming, who won a gold medal in the Olympics in 1968. "No one talks about the upside of cancer. Looking back on receiving that diagnosis, it took my breath away at first."
Actress Fran Drescher writes about how her uterine cancer was misdiagnosed as perimenopause for two years. "Many female cancers, when at their earliest, most curable stages, have symptoms that are almost identical to far more benign illnesses."
Sam Donaldson of ABC News writes in his blog about how it helped him to hear from others who survived cancer after he was diagnosed.
"I joined the Cancer Club in August of 1995, when a melanoma tumor was discovered in one lymph node in my right groin," Donaldson writes. "Cancer may not be contagious, but hope is, so, club members, let's spread it!"
Sen. Clinton's short blog promotes cancer research by giving statistics: "Nearly one in 8 women will develop breast cancer in her lifetime, and over 40,000 women will die this year from breast cancer alone."
In contrast, Chopra, health guru to the stars, writes about how to release toxic emotions, which he said are "harmful accelerators of disease." He also encourages people to "transform toxic relationships into nourishing ones."
"If you accept that reality is a selective act of perception and interpretation, the most empowering way to transform a relationship is to change the way you view the other person," Chopra writes.