You have been diagnosed with a horrible disease. Your life has been turned inside out and upside down. You are undergoing harsh treatments. Your hair is falling out. And always at the back of your mind is an insidious fistful of terror that won't let go: What if it's too late? What if I don't respond to treatment? What if I die?

You might think that at a time like this how you look would be the least of your worries.Not so, say those who have been there. Being told you have cancer is devastating. But one of the worst things, they say, is losing your sense of self. You look in the mirror at someone who doesn't seem to be you anymore. And that adds to the terror.

Looking good makes you feel better, says Barbara Alexander, communications director for the Utah Division of the American Cancer Society. "Evidence clearly shows that when we look our best it affects how we feel and may even enhance the healing process."

That's the reasoning behind the organization's "Look Good . . . Feel Better" classes that offer women undergoing cancer treatment an opportunity to learn about how to look their best. The program was developed in 1989 by the Cosmetic, Toiletry and Fragrance Association and the National Cosmetology Association in cooperation with the American Cancer Society.

Professionals in the cosmetology field donate their time to work with the patients. "We want to help women cope with the effects of diet, with skin changes, with hair loss, with people who may look at them funny," says Susanne Harwood, who works with the program. Harwood is not only a cosmetologist, she is a former cancer patient herself. "I had a brain tumor and was sent home twice to die," she says, before doctors were at last able to remove her tumor.

Kay Gravette, too, has been there. She was diagnosed with cancer first in 1990 and again in 1996. "I've lost my hair more times than I can - no, more than I choose to remember."

You don't have to look like you are ravaged by disease, they tell class members. And, you don't have to feel like you are alone.

And that support is an important part, says Marda Dillree, a cancer patient who has taken the class. "It means a lot to sit here with people who have gone through what you are going through, to see them looking beautiful."

Dillree, a state representative from Farmington, was diagnosed with non-Hodgkin's lymphoma on Dec. 31 of last year. She finishes her last chemotherapy treatment on April 24 and says her prognosis now is very good.

Dillree first attended a "Look Good . . . Feel Better" class in February and came back in April to share what she learned with a group of volunteers and others for a special session held in connection with National Cancer Control Month. "We want to let more people know about this program and how it can help them," says Alexander.

When Dillree was first diagnosed with cancer, she was devastated, she said. One of the first things she did was call a good friend who worked with the Cancer Society. "She came over with a huge bag of books, tapes, brochures and other materials. One of them told about this class. I wanted to make sure I did everything I could to make myself and my life as normal as possible," she says. "That was very important to me. So I took the class."

And, she says, it has made a big difference in her attitude. Despite her total hair loss, "people say they can't believe how well I'm doing. You go away from here thinking `I don't have to look awful.' That helps a lot."

It's a fact of womanhood, says cosmetologist Connie Ljungberg, that "hair and makeup make a big difference in how you face the world." She takes class members through a 12-step makeup process, explaining how to handle body changes and sharing some tips of the trade. "Your skin will act differently. It may be blotchy. It will be dry. It will be more sensitive to sun."

She demonstrates the best way to use blush to give a healthy glow. She talks about using eyeliner if you have lost eyelashes. "A soft line is much better if you can't use mascara." She talks about how to make eyebrows that will fit your face. "Lighter is better. If you've lost your eyebrows, you don't want it too dark." She talks about how false eyelashes are much better now than they used to be.

Each class member is given a box of cosmetics, donated by the industry.

Amy Nelson, a volunteer from Creative Wigs, talks about hairpiece options, about costs and care. Most wigs today are synthetic, she says, but very realistic-looking and easy to care for. Average costs range from $75 to $95, although some can go as high as $200. "They come pre-styled and pre-cut. You just wash in water, shake out and let air-dry." She talks about using a foam band to keep the wig secure. "Of course, when your hair starts to grow back, that stubble is just like Velcro, and that will keep the wig on."

Class members get to try on various styles, and they all get to choose one wig that has been donated for the Cancer Society's Wig Closet.

One problem with wigs, says Dillree, is they get so hot. "How do you do summer?" she asks. And that leads to a discussion about turbans and hats and other head-covering options.

Kay Gravette talks about how you can use pads to give turbans fullness or fringes to provide any kind of bangs you want. She demonstrates how to combine scarves and wired headbands with turbans and turbans with hats to provide different looks.

Cotton or rayon works best for scarves, she says; polyester is hot and tends to slip off the head. As your hair starts to grow back, you might want to try ballcaps or berets, she says.

"There is so much more on the market now," she says. Back in 1990, when she was first diagnosed, there weren't as many options. "There's been a big change, more awareness. Now you have more choices, stylish colors."

In 1998 an estimated 600,700 women will develop cancer. Breast cancer, the leading cause of cancer in women, will strike one out of nine women in their lifetimes.

But the good news, says Alexander, is that more than 50 percent of patients are surviving because of early detection and improved treatment. Of the woman diagnosed with cancer this year, an estimated 10 percent more would survive if their cancers had been detected in a localized stage and treated promptly.

Programs such as "Look Good . . . Feel Better" can help restore a cancer patient's self-image and appearance and help take the trauma out of treatment.

"The `Lipstick Theory' is an observation made by medical professionals that when a woman battling cancer starts to put on her lipstick, she is on the road to recovery," says William Cahan, senior attending surgeon at Memorial Sloan-Kettering Cancer Center in New York. "The premise is: If a patient can be helped to look good, she'll feel better and the quality of her life can be improved."