Breast Screening
False negative results
Breast cancer is the most common cancer in women, and mammography is the only screening method that can detect breast cancer early. However, mammography is not perfect. While early detection offers clear advantages, mammography also has potential disadvantages. These include the possibility of false positives, where something is seen on the mammogram but no cancer is found, and false negatives, where the mammogram may look normal even though breast cancer is present. This may lull the woman and her doctor into a false sense of security. A woman who receives a false negative result - one that shows there is no cancer when there really is - may delay seeking medical care even if she has symptoms.
False negatives occur in 1 of every 2,500 women screened (NHS Breast Screening Programme – "Helping you decide" leaflet July 2013) and occur more often in younger women than in older women because the breast tissue of younger women is denser. The size of the tumour, the rate of tumour growth, the level of hormones, such as oestrogen and progesterone, in the woman's body, and the skill of the radiologist can also affect the chance of a false negative result.
Some of the women we spoke with who attended for routine breast screening had false negative results. One woman explained that, after her first mammogram, she was recalled for further tests which all showed that she did not have breast cancer. Several months later, when she noticed 'something odd' in her breast, more tests showed that she did actually have cancer. Her cancer, however, had not been picked up by the radiologist who had read the first mammogram. She nevertheless encouraged women to attend for breast screening (see 'General views on screening').
More tests after her first mammogram showed that she did not have breast cancer.
More tests after her first mammogram showed that she did not have breast cancer.
They said that no it was not a cancerous tumour. It was some sort of fatty nodule that wouldn't cause me any bother at all.
And you should just leave it and it would be fine?
It would be fine and I would not need to be, one of the things they said to me, I would not need to be called in a year, because people who they were a bit iffy about they would recall in a year. My normal three-year recall would be fine.
The radiologist who had read her first mammogram had not picked up her cancer.
The radiologist who had read her first mammogram had not picked up her cancer.
And he pointed out the cancer in the one which would have been, well in the two that had been taken one week after each other. It was only like a, as the top of a pencil maybe, white spot. And he was saying to me, "Well you see it, how small it is?" But I was saying to him, "But, you are the, you're the expert. I don't see anything." I mean there were just funny black things as far as I was concerned. But he, but then he was the top man looking at them. Obviously the top man wasn't on that day and whoever did read them, didn't see that. But to see it six months later was amazing. Absolutely amazing.
It had grown that much?
It had grown that much. It, in fact, on those six month ones it was practically taking up half of my breast, on this photograph. Obviously not in the breast but in this photograph it was taking up half the breast.
Despite her experience of having a false negative result, she encourages women to go for breast...
Despite her experience of having a false negative result, she encourages women to go for breast...
A little, a little. Yes I had a little discussion with him but I really had decided before I went that, if that was the case, there was no point in going down that road. I mean, what was I going to do, sue them? Or was I going to make a fuss or? Because at the end of the day it wasn't going to change one solitary thing to my life. So, I just wanted to know for my own benefit, and perhaps give them a wake-up call that they'd look more carefully at someone else's. It wouldn't help me, but it might help someone else, that was my view on that.
At one point, you mentioned that you thought, oh mammograms are no good. Were, what was that time, what were your thoughts about?
Well my time, my thoughts at that time were, how did they miss it? How could they have missed it? I could have understood them having missed it if I had just gone for the screening and merrily on my way. But for them to recall me, and still miss it, I felt was beyond belief. That was what I felt. So I felt that mammograms were useless. But I have stopped thinking that. I have stopped thinking that. They are useful for a lot of people. A number of people in the [support] group will say, "They saved my life." They went for the, they were fifty, or whatever age they went. Something was picked up, they had the mastectomy, and they're living normal lives now which would not have been the case otherwise. So I know they are useful and I do know that they're not, they're only as good as the people who are reading them.
I think screening is a really good idea. I encourage everyone to go for screening. I don't, for all the sort, you know, at first I used to follow it up with, "Well, it was useless for me, but it might be good for you." I don't, I've grown out of that, I don't say that now. I encourage people to go and I encourage people who are over sixty, or sixty-five or whatever the upper age is, to go. You know, I say, "Go, make an appointment and go because it's worthwhile." I do encourage people to go. I think it's a good idea.
Mammography may miss some cancers. Some breast changes, including lumps that can be felt, don't show up on a mammogram. One woman said that, although her first mammogram was clear, four months later she discovered a lump that turned out to be cancerous. At first she was upset that her cancer had not been detected four months earlier, but then accepted that some lumps do not show on mammograms.
Her first mammogram was normal but a breast lump she found a few months later was cancerous.
Her first mammogram was normal but a breast lump she found a few months later was cancerous.
As time wore on and I was left waiting and waiting and I was called in to see the doctor. Well I think really I knew then that, what the diagnosis was, and I was told it was breast cancer. That was on a Tuesday and on Friday of the same week I saw a consultant who advised me to have a mastectomy, a full mastectomy. Which I decided to go for. So I was booked in for surgery inside a couple of weeks.
Was upset that her cancer was not detected in an earlier mammogram, but accepts that mammograms...
Was upset that her cancer was not detected in an earlier mammogram, but accepts that mammograms...
Yes, for screening yes, aha.
And that one was totally clear?
Yes. Yes.
And you just had a letter a few weeks later did you?
Yes, I must say now, I did, I felt very upset, I was very annoyed that when I was told by the consultant that I had breast cancer I thought, this can't be, how can this be? My mammogram was clear. But he informed me that there are some types of tumours, in his words, they hide, they can hide from a mammogram and a mammogram will not detect them, so that really worried me as well. I thought, well what's the point of having a mammogram if they can't detect all types of breast cancer? But I've been told, and I didn't really believe it at first, but from more information that I've read, that this can happen and it's just, it's one of the risks you take.
So that very first mammogram you had, that was in October?
October 2001.
And then, just about four months later?
Yes, I found a lump myself.
Breast changes can be especially difficult to spot on the mammograms of younger women because their breast tissue is dense. The NHS Breast Screening Programme invites well women (those with no symptoms) over 47 to attend for breast screening. A GP may refer women who discover breast symptoms between three yearly screens or under the age of 47 to a breast clinic for further tests (see 'Diagnostic mammograms in the UK'). These tests can include mammograms, MRIs, ultrasound scans, core biopsies and fine needle aspiration (FNAC) (see 'Referral to a breast clinic').
A younger woman we spoke to had been screened routinely since the age of 40 because of a family history of breast cancer. She had been referred for a mammogram between routine screens because of a bleeding nipple. She had a breast lump that did not show up on a mammogram. Although she had felt 'something' in her breast at the time, she dismissed it as nothing because the mammogram and ultrasound results were normal. Several months later, when she felt a lump in her other breast, she was referred to the breast clinic again and this time tests showed that she had cancer. This woman also discussed the false sense of reassurance that her original, normal mammogram had given her and felt that women should understand the limitations of breast screening.
Two younger women, who were not yet eligible for routine screening on the NHS Breast Screening Programme, also discussed having false negative results on mammograms that were done to investigate breast lumps they had found. One of them said a mammogram, ultrasound scan, fine needle and core biopsy all showed that her breast lump was benign. After she chose to have it removed by surgery, however, she found out the lump had actually been cancerous. This woman then had to have treatment for breast cancer (see our Breast cancer in women section). The other explained that, before surgery, her breast lump had not shown up on mammograms and both she and her doctors believed it was probably benign. However, after having it removed by surgery, she and her doctors learnt that it was cancerous (see 'Breast screening and younger women').
All the diagnostic tests she had showed that the breast lump she found was not cancerous.
All the diagnostic tests she had showed that the breast lump she found was not cancerous.
The mammogram also showed that it was clear?
Everything, everything, according to their initial tests, was clear. So the way I felt, I thought, well I would rather, I'd heard about people having breast, you know lumps and then it developing into something else or whatever so I thought, no I want to get rid of it. And that way, you've finished with it, that's the end of the subject and you can just move on.
After having her supposedly benign breast lump removed surgically, she learnt that it was cancerous.
After having her supposedly benign breast lump removed surgically, she learnt that it was cancerous.
So I went on my own, that's the first time, you know, because when I initially went for my check-ups I went with my husband. And he looked at me and he said, "you've come on your own?" I said, "yes, because I've just come to get the results" and he sort of looked at me and it still didn't click and he said, "oh well, good job we took the lump out because there are cancerous cells there and we need to do a marginal clearance around, we need to remove more of it and do a marginal clearance depending on the size of the lump.
And we also need to test for the lymph nodes because with a breast you get lymph nodes under the arm" so he said, "we need to remove those to check to make sure it hasn't started to spread because with the younger women, it moves very fast." And it was, so I thought, okay. I was sort of like, all right, okay, if that's what needs to be done, it needs to be done. And I just really didn't think much about it. I think, I obviously must have been in shock but I said, "okay" and he said to me, "okay, I'll write you a prescription for Tamoxifen and go and get this and you can get started on that and we'll arrange a quick appointment for you."
Her breast lump had not shown up on mammograms but when it was removed was found to be cancerous.
Her breast lump had not shown up on mammograms but when it was removed was found to be cancerous.
So I don't know exactly what happened at my next meeting with the Consultant, but he said "I think we'd better take it out now". I certainly wasn't clambering for him to take it out. I wasn't insisting he take it out. I was still, 'no it's fine'. He did tell me I think he thought he was 93 percent certain it was benign, it was alright, you know, I didn't expect anything to go wrong.
And the actual news that there was something wrong came on Friday afternoon, late afternoon and he said that there is something not right and to come and see him next week. So I didn't really understand it, but I knew enough, that it wasn't benign. That weekend I was just numb. I suddenly felt I'd joined a club I actually didn't want to belong to.
He said I'd need a further operation, a wide excision and I just I thought this can't be happening to me. I had a AA breast, I thought there isn't enough to have a lump in, let alone a malignant lump. There was breast cancer on my father's side of the family, although there was none on my mother's side. You know I thought I'm young, I've got virtually no breasts and here I have something that shouldn't be there and it's not fair.
So I raged a little bit, I went to see him. He really didn't explain it terribly well. He maintained it wasn't malignant, it was pre-malignant and anyway I had the wide excision.
Last reviewed March 2016.
Last updated March 2016.
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