Tumours that are less than 5 mm are rarely delineated on imaging. Tumours less than 1 mm are essentially never picked up on imaging… is this true?
I couldn’t comment on that but mine was 8mm on mammogram, 12mm on MRI and 16mm when removed. I’m assured it’s not fast growing just more accurate measurement each time. I was told it was tiny.
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Mine was 17mm and when I got results after there were two other 3mm ones which weren’t known about before (at least not known by me).
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On my routine mammogram, an IDC estimated at 9mm was discovered. On surgical extraction they found a bit of low grade DCIS next to it so the lump which was extracted measured 14mm. That first view of the 9mm IDC probably saved me a huge amount of bother later on. I must say, however, that my boobs rate A/B on the BIRADS scale so the more dense the breast, the more likely smaller lumps may be missed.
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Mine was picked up by routine mammogram and I couldn’t feel it neither could the BCN who examined me at second screening and it was 8 mm on mammogram and 6 mm on ultrasound . My first procedure was done as VAE but failed although they did get a bit of it . Another 6 mm was then removed as part of a wide excision 9 weeks later .
Not all cancers have what we might think of as a typical lump shape on film - I think that’s particularly true of lobular . Mine was tubular which is a very rare form of ductal cancer and when I was shown my original films ( as part of a meeting with my Radiologist a couple of years down the line ) it looked like a very slight thickening of one part of one duct . This is why I was called back for second screening but I’m surprised they spotted it at all . So I guess a cancer of less than 5 mm could go under the radar for one reason or another but I have read posts on here from women who have had cancers of less than 5 mm detected .
I’m not sure why you’re asking exactly but I hope you’re ok . Xx
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I had IDC and it was 14mm behind the nipple
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Thanks for all the replies.
I’m just upset because I was diagnosed back in October 2025, Grade 3 Her2 positive with a 7 cm mass as the tumours one 5.5 cm and the other 2.3cm were so close together.
I had previously visited my GP several times before that between 2021 and 2023 complaining of various symptoms and asking for a breast examination. On every occasion I was never ever referred for an ultrasound even though it runs in the family.
Fast forward to today I was just discharged from hospital after undergoing a diep flap mastectomy which took 11 hours in the theatre and I am temporarily immobile with a 3 and 7 year at home. Unfortunately I also received some updates regarding a medical negligence claim on the same day I was discharged that my claim wouldn’t be successful because if I had been referred for a scan back in 2021 or 2023 none of the tumours would have been detected i.e the original question. Well how do they know what size they would have been back then? Unless I was having regular scans between 21 until now, who’s to say they wouldn’t be detected?
Just feels like a slap in the face. Just gone through 6 months of chemo which left me in hospital many times and now just had this surgery.
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Hi bless,
I am so sorry you have gone through this. I found my cancer 22 months after a routine mammogram which didn’t pick up any sign of breast cancer. I have dense breast which as well as being a risk factor for developing breast cancer, dense breast make picking up a cancer more difficult. I also wonder if my cancer was missed as it was 25mm when removed. I eventually came to the conclusion that I had to deal with the situation as it was and fretting over past events were not going to change what I was dealing with now. I hope you recover soon from all your treatments.
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It very much depends I think. a suspicious area on my left breast was picked up on a mammogram and I had to have an ultrasound and biopsy. The diagnosis was that it was 2.2mm in size.
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Oh that’s awful - a real slap in the face after you feel like you’ve already been kicked in the head like you say .
I am assuming that your team has provided documentation to support your claim so it might help to speak to your BCN and try to get them to ask your Consultant about this . You might have to wait until your pathology results are all back but that might give an indication of how long your cancer might have been present . You could also ring the Breast Care Nurse Helpline on this site and talk it through with them and see if they can give you more information including on any questions that you now have because of what the insurance company has said . They may be right but there are ways and ways of delivering bad news and it should not involve giving you more questions than answers.
My insurance did pay out as have many others but a few people have had problems . There may also be a case for you to put in a complaint against your surgery by the sounds of this . Take care , the priority right now is your recovery and I hope that goes well . Xx
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Wow, thank you for sharing. This just debunks that theory that any tumour size less than 5mm wouldn’t have been picked up as abnormal and investigated further., also there is no definitive way of knowing that mine would have been less than 5mm back then without actual evidence from a scan.
The issue is when I visited my GP his exact words to me were that “it’s just lumpy breast tissue which is normal and that I was young and healthy”
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Sorry you’re going through this. I would report your GP. They are contractors working for the NHS and if they are not providing the right standard of care, it should be reported.
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Hi Bless, I’m so sorry you’ve had this experience. Was there any DCIS in your final pathology results? I was told that DCIS can be in place for years and can develop into IDC later on. My DCIS was flagged on scans whereas my IDC was too small to be visible, but presented itself after the post-surgery results. In other words, DCIS could have been visible on the scans much earlier.
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Hi bless,
Sorry you are having such an awful time.
I went to the GP with a slight dimpling of the breast . My mammogram was clear!! However the ultrasound suggested a tumour of 18mm, the MRI afterwards said 9mm, but when removed, the tumour was 35mm!! It was invasive lobular cancer.
So, I think what I’ m trying to say is these tumours can be difficult to find or assess, even with all these different scans?.
It’s such a difficult thing to have a cancer diagnosis. You have been through a lot. It may be an idea for you to chat to the BCNs or the Macmillan phoneline to get some more support?
Good luck and hugs x
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Thanks for reminding me about this because my diagnosis actually refers to me having extensive microcalcifications to a 70mm total area , these calcifications would have certainly been growing for years, investigated and most likely picked up as DCIS back then.
Referring to my breast as normal lumpy breast tissue and knowing my maternal grandmother had breast cancer was more than enough reason to be referred but the experts think a tumour would have been too small to be detected. DCIS just proves it isn’t all about tumour size.
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I second chatting to Breast Cancer Now who might have a helpful take on this.
I’m 73 and I self referred myself for a mammogram called back but didn’t think anything of it but was found to have a 2mm cancerous lump that is a grade 2 invasive that even the surgeon couldn’t feel had biopsy same day plus marker following week a tag and sentinel node scan with a tag next day lumpectomy and removal of 3 lymph nodes I’m now 2 weeks post op with results on June 10th happened all to fast for me
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Mine was so small it was invisible. It’s called Occult Cancer. The cancer was in my lymph nodes but they never found any primary in my breast.
I second that!
I was diagnosed last summer with 15mm IDC. I found the lump. It’s not in my family.
Curiously, I had been visiting the gp on a regular basis prior to finding the lump and on each occasion, trying to explain that I felt like something was ‘off’. The response I got from all of them was “menopause, menopause, menopause “ there was never any thought to look deeper. No blood tests up until the day the lump was mentioned- by me.
When I was examined by the GP, he confirmed the lump but then told me that I didn’t “meet the criteria for a fast track referral “. I was aghast! I said “I have a lump! What else do you need?”
We had a frank exchange of opinions and the upshot was, he asked me if I would like him to “try”. YES!! And I’m glad I insisted because I had cancer. Probably had it a long time. Almost as long as I had been trying to get a gp to have a proper look at what might be causing me to feel “not right”…
Since then, they’ve also picked up on other issues that are likely all related, but only since I insisted that day. Completely exasperated at banging my head against a brick wall of “urgh, another moaning menopausal pain in the ass” …
Several years ago, my hb had a serious heart condition, was hospitalised etc. when they discharged him, the senior sister on the ward took him to one side and said “be a pain in the ass, you’ll live longer”… wise words…
The moral of this?? Be your own advocate. Ask your questions and if you hit a brick wall, use a sledgehammer!
To the lovely lady with the insurance company issue: definitely don’t give up. insurance companies often refuse at first but if you persevere (which is a big ask, given what you’re going through), you might find a different outcome. Either that or at least you’ll know you gave it everything you can and forced them to explain their refusal. It might give you something to focus on, that’s proactive.
In any event, I wish you luck 
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