There are affairs, divorces, drug abuse. But no secret is as carefully guarded as a celebrity suffering with a chronic illness. Acknowledging publicly that you're ill could mean instant unemployment.
Like the DMV, the studios insist that production companies have insurance before anyone steps on the set. If a star is sick enough to cause even the slightest delay in filming on a multimillion-dollar movie, it's almost impossible to find coverage. It's almost easier to have all the details of your personal relationships revealed in the tabloids than to admit you're battling an ongoing illness.
A-list producer Lauren Shuler Donner wants to end this conspiracy of silence and discrimination.
Over the last two decades, she has produced some of Hollywood's most popular -- and profitable -- films, including "Pretty in Pink," "St. Elmo's Fire," "Dave," "Mr. Mom," "Free Willy" and all the "X-Men" movies.
And she did it all while battling the autoimmune disease lupus, as well as breast cancer.
"I know there's a stigma that has made it hard for people to acknowledge it, if they're sick," said Donner, who was cured of her cancer but is still living with lupus. "I didn't tell anyone I had lupus for many, many years, and I didn't tell anyone I had cancer.
"I was afraid no one would hire me, and I also felt it was deeply personal. It was nobody's business. Now, of course, my feelings have changed."
Because of that change, she has become an outspoken proponent for lupus awareness and treatment. Last month, she was honored for her efforts by Lupus LA, a group founded by Donner's doctor, Daniel J. Wallace, whom the producer credits with helping her cope with the chronic and potentially fatal disorder.
"I wanted to tell people you can live a full life, even if you're not feeling well," said Donner, who is working on seven films at the moment -- including more "X-Men" movies and a screen version of "The Secret Life of Bees" -- and will receive her star on the Hollywood Walk of Fame in October. "You can learn how to achieve on the same level as someone who is not handicapped by their health."
Donner said she was diagnosed with lupus, which creates a toxic stew of antibodies that can attack virtually any healthy organ or tissue, more than 20 years ago.
"When I was in my 20s, I was always sick," Donner said, sitting comfortably on a plush couch at her Beverly Hills production company. "I was always feeling exhausted. I had a fever all the time, and no one could diagnose me."
Finally, she found Wallace, who recognized her illness and gave her the treatment necessary to live. All the while, she continued to work, making film after film in an industry that doesn't always value female producers, let alone ones quietly battling disease.
Getting through it required Donner to change the way she lived. She learned to meditate, stay on her treatment, control her stress level and eat right. She admired celebrities such as Melissa Etheridge, who worked bravely in the public eye while battling breast cancer. It prompted Donner to also speak out about her condition, which she has started to do increasingly in recent months.
But holding up her record as one of Hollywood's most successful and prolific producers, perhaps she can help change minds in the industry's executive suites.
"Almost everyone I know is battling something, whether it's allergies or depression," she said. "Whatever it is, it makes you feel less than who you are. I believe part of life's challenge is to work through that.
"I want to show people that you can still live a life. You don't have to be defeated by illness."