A Guest Post by Sarah Wickens
I have something called occult breast cancer. I never heard of it before. Few have — even the doctors who treated me.
“Very rare.”
“Extremely uncommon.”
“Medical mystery.”
“We don’t know why.”
Each of those phrases was said to me at some point by various members of my medical and/or medical oncology team, referencing what they called the “occult” nature of my breast cancer diagnosis.
I’ll admit. None of it inspired a whole lot of confidence. Being the type of person I am, and wanting to go public with my diagnosis to try and raise awareness about breast cancer, how was I supposed to explain something that the experts could hardly understand?
What does the “Occult” part of Occult Breast Cancer Mean?
Occult Breast Cancer (or OBC) is defined as a “clinically recognizable metastatic carcinoma arising from an undetectable primary breast tumor”. [1]
In plain English? They determined that I have breast cancer, but there has never been a detectable tumour in either breast. They generally assume there was cancer in my breast at some point, but by the time I saw a doctor and had imaging done, it was most likely gone.
When I was diagnosed, I had a lot of trouble wrapping my head around the concept of occult breast cancer. I also had trouble finding information about it. I learned it is rare (they estimate that somewhere between 0.1% and 1.0% of all breast cancer cases are occult), so there isn’t a whole lot of guidance or information out there.
But what I can tell you for sure: I have Stage 3 Triple Negative Occult Breast Cancer.
Hunting in the dark
In July of 2024, my husband and I were on our first-ever European vacation. We were staying in a very Art Deco boutique hotel in Barcelona. Imagine black-painted walls, moody downlighting, a blanket artfully draped over a spindly chair in the corner of the room, and heavy dark curtains leading out to a wrought-iron balcony. You wouldn’t think that this environment would be conducive to discovering cancer, but in fact, I feel as though I wouldn’t have caught it if it weren’t for that room.
I was shaving in the shower on our second-last day in the city. The dark black bathroom combined with that “moody downlighting” cast a shadow on my armpit that I almost didn’t notice at first. Little did I know that action would set off a series of discoveries and events. I took a second glance, compared it to my other armpit, then did the same in the mirror, and walked out into the bedroom with my arms above my head asking my spouse, “does my right armpit look swollen to you?” From those actions would lead to months and months of chaos, terror, confusion, and ultimately, to discovering a strength I never knew I had.
The dangerous/scary part about occult breast cancer is that it can easily be missed with routine self-exams. This is primarily because we’re taught to inspect our breasts, not our armpits. Occult breast cancer can also be missed on annual mammograms if the imaging doesn’t capture enough of the armpit region. Therefore, occult breast cancer is often not caught until it’s already progressed to Stage 4.
I was very lucky.
It turned out that my swollen armpit was a result of the breast cancer, which had spread extensively throughout my right axillary lymph nodes (or armpit lymph nodes). My largest lymph node was initially measured at 4.8cm x 3.5cm x 1.6cm on ultrasound. It later measured at 3.1cm x 1.6cm on MRI, and two other nodules were detected measuring 1.4cm x 1.0cm. Multiple other lymph nodes also appeared abnormal. In total, I had somewhere around a dozen lymph nodes that were suspected to have cancer.
This is an image from the PET/CT scan I later had. See all of those bright white spots? They are the breast caner cancer nodules that lit-up in my right armpit.
But how can they diagnose you with breast cancer when you don’t have a tumour in your breast?
To answer this question, it’s easier to start with the theories of what causes occult breast cancer — or at least the ones that I’ve read and/or been told about:
1 – The original breast cancer tumour migrated out of the breast and decided to make my lymph nodes its new home
2 – The tumour in my breast was still very small when the cancer spread to my lymph nodes; small enough that my immune system destroyed it. By then it was too late – the cancer was already en route to my lymph nodes, or had already established itself there
3 – The tumour never fully formed in my breast, and the small microscopic cancer cells never clumped together, rather they headed straight to my lymph nodes
4 – There is a tumour there, but it’s so tiny that it’s undetectable with current scanning technology. Perhaps through advancements in AI it might be detected.
In other words, they diagnosed me with occult breast cancer because of my lymph nodes.
Between August and September of 2024, I saw my family doctor, had a mammogram of both breasts, an armpit ultrasound, a mammogram with contrast, then an ultrasound-guided biopsy of the biggest “suspicious” lymph node in my armpit. That biopsy was sent to a lab, where they were first able to confirm that my lump was indeed cancerous breast tissue that had spread to my lymph nodes.
I received my occult breast cancer diagnosis in October 2024, the day after my 43rd birthday. This phone call was the first hint that I was about to play a part in some sort of medical mystery. My family doctor called with the news, adding “they’re saying they can’t find the primary tumour, and I’ve never heard of that before.” He’s a fantastic doctor. I think he was just flabbergasted. Occult breast cancer is so rare that unless you are a clinician deeply immersed in the world of beast cancer, most people have never heard of it.
One of the first questions I asked my surgeon was, “Are we sure this is breast cancer? Could it be lymphoma?” I was assured that the laboratory testing was correct. This diagnosis could only be breast cancer.
This is an image from a PubMed article that describes a couple of case studies of Occult Breast Cancer patients [2]. Here you can see that there are no tumours in either breast. You will also see the arrow pointing to the cancerous armpit lymph node(s).
How does the occult part of the breast cancer diagnosis change the journey?
Typically, an occult breast cancer journey means more testing as the doctors try to hunt down any sign of a breast tumour. It also meant my case was passed along to different people.
However, the biggest change as a result of an occult breast cancer diagnosis happens when it comes to surgery.
Between November and December of 2024, I saw my surgeon, got the extended pathology from my lymph node biopsy which confirmed triple negative breast cancer, had my first round of bloodwork done, had an MRI, had a PET/CT, met with my oncologist, had an MRI-guided biopsy of some small suspicious breast spots which turned out to be PASH (nothing of concern), had an echocardiogram, had my port installed, and then started the Keynote-522 chemotherapy protocol just four days before Christmas of 2024.
Somewhere along the way, my surgeon called and told me that she was referring my case to a more experienced surgeon. She had never dealt with occult breast cancer, and was concerned that her scorched-earth remove-everything recommendation might not be the best approach. Before we even knew the stage of my cancer, she had recommended a double-mastectomy and the removal of every single lymph node in my right armpit area (called an axilla clearance). I was sent to a surgeon in the nearest major city, who happens to also be the director of the breast care program at the surgical hospital. Even my new surgeon, as experienced as she is, had seen fewer than a dozen cases of occult breast cancer in her career.
In terms of a surgical recommendation, there wasn’t one when it came to my breasts. The absence of breast cancer in the breasts is a “grey area” (her words). She gave me the option of a double mastectomy for peace of mind. As far as lymph nodes, she recommended only removing the affected cancerous ones.
But first, I needed six months of chemotherapy, with my final infusion landing in May of 2025. A week before that last infusion, I had a follow-up MRI, which found no evidence of cancer anywhere in my lymph nodes (yay!!). While that doesn’t mean the cancer is gone; it does means the MRI couldn’t detect it anymore.
Choices, choices
As a result of my good response to chemo, I opted to keep my breasts. A lumpectomy wasn’t an option because there was never any detectable lump. I felt (and still feel) confident that because chemotherapy was able to eliminate the huge cancerous masses in my lymph nodes, it surely attacked any teensy tiny little mass that might have existed in my breast.
I had my lymph node removal surgery only a few days ago. They removed three sentinel nodes to send for pathology. The results of those findings will determine whether they need to go back in and take more lymph nodes. And, if we discover the cancer is more extensive in my lymph nodes than we thought, a double mastectomy is still an option.
My surgeon tells me that with my chemo response, a mastectomy versus keeping my breasts has a near-identical recurrence rate. So, I’m comfortable with getting scans every six months going forward for the next few years.
Radiation will happen in the next month or two, and my surgeon is recommending whole breast radiation on my right breast and radiation to my right armpit. I don’t know how many sessions I’ll have yet, but my surgeon estimated it’ll be four to five weeks or 20-25 sessions. I am also receiving immunotherapy treatments until the end of 2025.
My diagnosis of occult breast cancer is incredibly rare. My options around surgery — especially when it comes to breast cancer — are not going to be everyone’s choice. There is no “right” or “wrong” diagnosis or choice; there is only our individual choice. We can only choose the option that follows science and the recommendations of our doctors, and that gives us peace of mind.
Additional reading & references:
[1] [2] “Occult primary breast cancer: Two cases report and literature review”:
https://pmc.ncbi.nlm.nih.gov/articles/PMC10667777
“Occult breast cancer: Where are we at?”:
https://pmc.ncbi.nlm.nih.gov/articles/PMC7599122
“Clinicopathological characteristics and treatment outcomes of occult breast cancer: a population-based study”:
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-022-01472-8
About Sarah Wickens
I’m 43 years old, living with my common-law spouse of 14 years Luke, and our senior dog Skills in the beautiful little town of St. Marys, Ontario. We do not have any children.
I’ve worked for the past 11 years in the Automotive Industry, and prior to my diagnosis was on the career path towards a leadership/supervisory role at work. I never thought I’d say “I can’t wait to go back to work!”, but after more than six months of being cooped-up indoors with very little social interaction & little energy to do more than lay on the couch most days, I’m definitely ready to go back. I still have at least a few more months to go, but I’m looking forward to feeling “normal” again, whatever that means.
As I write this, I’m also really looking forward to October’s CIBC Run for the Cure (or in my case, most likely a Walk for the Cure!). I’ve already managed to raise nearly $3,000 for my team!!
I’ll end this with a phrase I’ve been using for months: if you have boobies, or if you know someone with boobies, please get them checked! If you’re 40 or older and in Ontario, Canada, you can self-refer without a doctor’s requisition through the Ontario Breast Cancer Screening Program. And please, make sure to check your armpits as well.
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