I discovered the lump on a brisk, crystalline day while lying on a Maine beach with old friends. Located just above the top of my bathing suit, it was small, smooth and freely movable. For a moment or so, I rolled it around between my fingers to see if it was attached to anything. It didn't seem to be.

I continued to lie in consternated silence, hoping that it would miraculously disappear. My first inclination was to dismiss the thing; I had had a negative baseline mammogram just six months before. Surely, no malignancy could have developed so fast. On the other hand, I have inherited a family trait of viewing any abnormality as guilty until proven innocent, and this was a perfect specimen.

Half an hour later, sitting in an emergency room with time on my hands, I finally calmed down enough to review the situation. For starters, there had been nothing abnormal to see in my breasts in February, and now there clearly was. Whatever it was did seem extremely small, however. Could I be mistaking it for something else? But no, the lump was too discrete, too compact to be a simple thickening of the skin, too visible when I arched my back to be a cyst. And yet I was sure that I could not just have missed it in checking my breasts the month before. So it had to be new, very young, and therefore, as far as I knew, found in time. Probably it wouldn't be malignant . . . or would it? And was I absolutely sure that I had checked my breasts in July? In short, I was thoroughly confused.

The doctor on duty was reassuring but cautious. "It certainly feels like a fibrocystic mass," she said, "and 95 percent of these are harmless. But you will want to check out the other 5. Do it next week when you get home, there's no rush. And enjoy your vacation."

Her calm, and the suggestion that there was no hurry, got me through the evening. But as I lay awake in the night, I decided to leave for home in the morning.

Heading south toward Boston on I-95, still taking comfort in the mammogram, I began to feel shaky. My own doctor at the Massachusetts Institute of Technology Health Service was as reassuring as the one in Maine. The lump was small, smooth, freely movable -- all the things you want a lump to be. Nonetheless, he wanted me to have a mammogram as soon as possible, just to make sure. How about the next morning?

The following afternoon my physician called, sounding abashed. The mammogram was inconclusive, but the sonogram suggested that the node was solid -- not filled with fluid as a benign cystic mass usually is. He was clearly surprised with the reading but urged me not to be disheartened: This node was only slightly larger than a BB, and sonogram machinery works most accurately on masses of one centimeter or more. Only a biopsy could tell us for sure. He already knew that the chief of surgery at MIT had an opening on his "minor procedures" calendar for the following Friday.

The biopsy itself turned out to be indeed a minor procedure. The node was so small it took only minutes to excise. The surgeon could not recall ever having seen a node much smaller and, like my personal physician, was reasonably sure it was caught in time. It was too bad that the weekend ahead meant there would be no results until Tuesday, but I was cheered by his optimism. Waiting, this time, seemed nowhere near the punishment it had at midweek.

Yet on Monday morning we discovered just how misplaced our optimism had been. The results were in earlier than expected and they were conclusive: This tiny lump, the size of a shrunken pea, was malignant.

I do not remember formulating any conscious plan for the next few days, but everything that happened was more or less controlled by the fact that surgery was scheduled for only eight days later. I was so busy I had no time for the anger or why-me spasms apparently common to people with life-altering illness. What I got to know all too well was cold, gray pessimism and a kind of forlorn resignation. Why shouldn't it be me? It was an undeniable relief to have to make a lot of important decisions in just a few days. Moving at full throttle through one medical consultation after another kept daytime fear in check. At night, however, I worried endlessly about everything, mostly about my two teen-agers: Would I live to see them into adulthood? Would they miss me if I didn't? Could they live without my constant attention and love?

In due course, however, I found myself emerging from my state of shell-shock into an almost equally uncharacteristic state of high spirits, more like a Girl Scout with her first solo campout ahead than a practical, responsible 44-year-old working mother.

Then, as I started to evaluate the possible options for treatment, i.e. to take charge of my illness, the chaotic mental activity of my nights came to a halt, as well. The oncologist I saw seemed to understand this process very well. As I thanked him for squeezing me into his already jammed schedule, he smiled and said: "That's O.K. The brain rests easier the more you know about your alternatives."

That chaos is the product of an overactive imagination, I am well aware. My problem was that I seemed unable to make practical use of that knowledge. It was a therapist who helped me break out of my rut. My first response to my diagnosis had been to keep it as much a secret as possible. "That's just wrong," she said with uncharacteristic bluntness, "You want to talk about it. Talk to anyone who will listen. Talk to friends and family. Call everyone you know if you feel like it. But whatever you do, don't hide anything."

So over that week I did discuss my hopes, fears, perplexities; anesthesia and breast surgeons; postoperative treatment and recovery; mammography equipment; love; other women's experiences with maybe 50 people ranging from family members to the head of the research group at MIT to which I am attached, to my oldest friends from baby-raising days in Buffalo. I talked to students, faculty members, lingerie saleswomen, my pastor, neighbors, even the friends of my kids who, as they dropped in for a visit, would comment on how hard it seemed for them to talk about their mother's dilemma.

Well, if my children were silent in their own fears, their mother was not. Over the 16 days between my discovery of the lump and the mastectomy I chose to have, I must have asked a million questions and gotten twice the number of answers. What I heard helped clarify the picture but also made me feel increasingly positive. So much amassed information could only protect me from being bulldozed by the unexpected, and that was comforting. I still cried occasionally, and I felt as if I couldn't bear another morsel of advice. But the therapist was so right: Talking was my salvation. It made it possible to contemplate the worst without caving into fear.

Had I succeeded in my original plan to isolate myself in my illness, I would never have discovered that talk would also give me access to the possibility of survival, the chances of which I had more or less stopped thinking about when the biopsy results were positive. In my initial confusion and terror, all I could remember was that there are only two survivors among my dozen friends and acquaintances who have had breast cancer. Fortunately, the people I talked to knew of many more. In my anxiety, I had ignored the fact that many women do live long lives despite breast cancer. Optimism, I learned, doesn't come naturally but must be cultivated.

It may seem strange to take comfort in numbers (for once the words ride above the cliche'), but as first one doctor and then another would refer to how common breast cancer has become, I felt better. There is no mystery; doctors see it daily. The difference is in the prognosis, and that depends on the condition of the tissue removed. One's life does not hang on how well this routine surgery is performed but on what is learned from it. As I conducted my week-long crash course in mammary malignancy, the afflicted breast seemed to become more a separate object and less a part of me, something to be rid of -- perhaps mourned later -- but definitely hostile territory.

As the crucial day approached, I found myself looking forward to it with a curious mixture of detachment, apprehension and elation. By the time I walked into the operating room, I regarded this excision as the best thing that had ever happened to me. I expected to survive the surgery, but I was unprepared for the anxiety of awaiting the results of the biopsy Confined to the infirmary and mildly uncomfortable as well, diversions were harder to come by this time. But when the surgeon finally called with the results and they were unbelievably favorable (no cancer in the marginal area around the site, no spread into the lymph system), I found out what an excellent job of preparing myself for the worst I had done. The news simply would not penetrate. It was hours before it did and the next day before I could believe that no chemotherapy would be needed.So what should we conclude from this tale? In a nutshell, that the monthly self-examination is the key to surviving breast cancer. Of course, I'll keep having mammograms -- they are the best way to detect cancer early. But when they reveal nothing, I won't be lulled into thinking that I can have a holiday from self-examination.

I have half as much breast tissue to inspect now than I did on that last miserable day of vacation, but I shall do it with twice the care.

Natalie Frohock Tarbet works at the Laboratory for Computer Science at the Massachusetts Institute of Technology and is a free-lance writer in Boston. Her first-year mammogram in September and quarterly examination showed that she remains free of cancer.