A device worn in a brassiere and designed to detect a breast cancer by its heat could be on sale in a year, if tests go well.

The "if" is large. The device has not been thoroughly tested, and human trials could take more than a year.

The studies will start soon at several medical centers, including Georgetown University here, the device's backer -- the perfume firm Faberge -- said yesterday.

"The first cancer is probably no bigger than the dot made by a pencil," said Dr. Harold Karpman, Faberge medical director. "It doubles in size every four months. With a heat test, the hope is that cancers the size of a pinhead can be detected."

Georgetown Medical Center Drs. Betty Hamilton and Bruce Shnider have completed a study in which the device -- made of wafer-thin pliant material containing heat-sensitive chemicals -- proved accurate in measuring skin temperatures.

Cancer cells often multiply rapidly and emit heat. In the breast, deep veins can carry this heat swiftly to the surface, where it should change the device's color.

The same principle is involved in thermography, a method of breast cancer detection used in doctors' offices.

Some breast pathology was detected with the device in a preliminary test in 28 New Jersey women.

"Theoretically, the method should work," Hamilton said. She had 50 women tuck the device inside their bras for periods ranging from five minutes to an hour.

The device's readings were checked at the university and proved to be accurate within a degree -- close enough to be called reliable -- said Shnider and Hamilton.

The Georgetown doctors plan to have 250 women aged 38 and older wear the device for 15 minutes once a month for three months. Then the doctors will check the women by standard means for cancer or other breast problems that heat might also reveal.

Next, Karpman said, the device will be tested on women who are about to have biopsies for suspected breast cancers. In this way, any "positives" turned up by the device in the bra will be checked against a surgeon's findings.

The device is made by BCSI Laboratories. Faberge has bought rights to acquire up to 80 percent of BCSI's common stock during the device's testing. If the device is successful and is approved by the Food and Drug Administration, Feberge will handle the early marketing.

Breast cancer detection by office thermography once was hailed as a great advance. But tests turned up too many false readings to make the method reliable enough for mass use.

Thermography is still used in diagnosis in some hospitals. And some doctors believe that, read properly, it could become a safe, accurate method for wide cancer detection.

The American Cancer Society currently advises monthly breast self-examination by all women over 20, breast examination by a doctor every three years for women from ages 20 to 40 and an annual doctor's examination for women over 40. The society also urged women to have one baseline mammogram, or breast X-ray, between 35 to 40, and annual X-rays after 50.