Columnist Ellen Goodman suggested that the whole thing was a "good-taste-ectomy," and there were rumors that even the president's bedpans had mysteriously disappeared into the nether world of the souvenir hunter. But President Reagan's operation for colon cancer in July at least briefly motivated the over-40 set toward checkups for colorectal cancer and suggested the importance of a new era in which, ideally, the Big Mac or the Whopper is traded in for a bowl of high-fiber porridge.

Reagan's bout with cancer, and the openness with which it was discussed, probably saved a few lives.

Some new approaches to resistant cancers such as colon, lung, rectum, skin and kidney were disclosed last year, pointing to better therapies with fewer side effects for more victims within the next few years.

The most dramatic announcement came last month from the National Cancer Institue, which is experimenting with biological response modifiers (BRM). This approach involves the use of genetic engineering to enhance a patient's natural disease-fighting mechanisms enough to zap cancer cells wherever they may have spread in the body.

In the NCI technique, a patient's white cells are extracted and enhanced with a natural hormone called interleukin-2 to turn the white cells into natural cancer killers. It received widespread medical and public attention, including unusually fast publication of results in the prestigious New England Journal of Medicine.

But some noted that the flurry of attention seemed reminiscent of the hopes attendant on interferon in the 1970s. Interferon, another biological approach, produced some short-term shrinkage of cancer cells but fizzled as an all-out cure. After the initial flare of publicity over the newest technique, NCI officials disclosed that one patient on the new treatment had died, possibly because of potentially fatal reactions to the treatment.

Biological response mechanisms are being sought to replace surgery and chemotherapy which often seriously impair a patient's quality of life, with often only marginal survival advantages.

Another approach, using monoclonal or polyclonal antibodies, treated to selectively seek out cancer cells, has been found effective in treating advanced liver cancer by researchers at Johns Hopkins University in Baltimore.

This approach, in which patients have been followed for up to three years, is regarded as a major breakthrough because of the resistant -- and usually fatal -- character of advanced liver cancers.

Breast cancer patients can now receive the anti-estrogen agent tamoxifen citrate -- marketed as Nolvadex -- which was approved by the Food and Drug Adminstration in December for use along with chemotherapy in adjuvant, post-surgical breast cancer treatment of postmenopausal women who have evidence of cancer spread to their underarm lymph nodes. British studies have demonstrated the usefulness of tamoxifen alone as an adjuvant therapy in postmenopausal women with hormone-positive tumors and no evidence of spread, and a National Institutes of Health consensus development conference recommended its use for that group -- as many as 27,000 cancer patients of the 120,000 expected to be diagnosed next year.

But FDA regulations require U.S. studies before it can be approved for use as the sole therapy, and only those combined with chemotherapy have been submitted so far. Tamoxifen has many fewer side effects, is much less expensive and possibly, in some cases, more effective or just as effective as the more aggressive therapies. Studies continue.