APPENDICURE

Why a patient asking “is this actually a plan?” is asking the right question, and what the published protocols say.

This post was already drafted. I had been chipping away at it for a few days because I keep hearing different versions of the same frustration from LAMN patients, and I had not yet seen anyone put it into writing. Earlier today I posted a piece on the high-grade side, on why it matters for high-grade patients to be counted in the Appendicure patient-led data registry. The LAMN piece was supposed to go up next.

Then I had a colonoscopy of my own this morning, came home, and pulled up the community feed tonight to find a patient post that read like it had been written specifically to anchor the piece I was already drafting. So I dropped her note in, edited around it, and that is why this is going up later than I planned.

Here is what she wrote, lightly trimmed:

“I am almost three weeks post-op for incidental LAMN, grade 1, pT3, and I just had a frustrating follow-up at a major center. After a long commute, I waited two hours for a five-minute talk that left me with more questions than a plan. My path showed acellular mucin at the margin. My CT and intraoperative findings were clean. They ordered CEA and CA 19-9 now, and CA-125 alone in a year. They ordered a chest and abdomen CT in a year, with no pelvis. They referred me to a LAMN clinic for a one-year visit with no intake, no interim contact, no instructions. I do not want to over-treat, since my recurrence risk is low, but I feel like I have been given placeholder orders instead of a cohesive plan. How was your surveillance structured at the big centers?”

That last line is the one I kept coming back to. She was not asking for aggressive treatment. She was asking whether what she got actually counts as a plan.

I have actually heard that question a lot.

LAMN sits in a strange spot. Recurrence risk is genuinely low for most patients, but low risk is not the same as no risk, and a clear plan is not the same as a heavy plan. What she was describing was not over-treatment versus under-treatment. It was under-defined care. For appendiceal cancer patients, that is a meaningful distinction, and worth taking apart.

It is also a distinction that exists partly because the evidence base for LAMN surveillance is thin, and the evidence base is thin partly because most LAMN patients are never counted in anything. I will come back to that at the end. For now, let me walk through what she is dealing with, piece by piece.

1. Acellular mucin at the margin

This is the finding generating the most worry, and it is also the most commonly garbled phrase in a LAMN pathology report. Before I get into what the studies say, I want to slow down on the phrase itself, because two different findings get described with similar language and they carry very different weight.

Two findings, one phrase

Acellular mucin means mucin without tumor cells. Where that mucin sits is what changes the conversation.

Acellular mucin at the proximal appendiceal margin refers to the surgical resection edge, the cut line where the appendix was separated from the cecum. The pathologist sees mucin sitting at the inked edge of the specimen.

Acellular mucin on the serosal surface or in the right lower quadrant refers to mucin found outside the appendix wall, on the outer covering or in the surrounding tissue. This is what staging systems mean by extra-appendiceal mucin.

Both can show up on the same kind of report, sometimes with overlapping wording. If your report says “acellular mucin at the margin” and you cannot tell which one it means, ask. The surveillance conversation is different in each case.

What the studies say about each

These two findings have been studied separately, and the data does not support folding them together.

On margin involvement at the resection edge: the College of American Pathologists protocol notes that the prognostic significance of acellular mucin pools at the margin has not been adequately studied and is not currently considered a clear indicator of residual disease. A frequently cited surgical pathology review concluded that involvement of the appendectomy margin by neoplastic epithelium or acellular mucin has not been shown to predict recurrence on its own, even without further surgery. A 2024 structured surveillance program followed a small group of margin-positive LAMN patients without re-excision and did not document recurrence or progression in that subset, while flagging that the cohort was small.

On extra-appendiceal acellular mucin: patients with acellular mucin found outside the appendix have reported recurrence rates roughly in the 3 to 7 percent range across several series. A 2024 Mayo Clinic cohort of 125 LAMN patients confined to the appendix and the limited right-lower-quadrant area showed a 5-year cumulative recurrence rate of 3 percent. The same structured surveillance program found a progression rate of about 3 percent in patients without extra-appendiceal mucin and around 20 percent in those with it. When extra-appendiceal mucin contains cells, recurrence risk climbs higher.

So the literature lands in two places at the same time. Resection-margin involvement, on its own, has not been shown to drive recurrence. Any extra-appendiceal mucin, even acellular, moves a patient into a more attentive surveillance category. Most experienced appendix programs hold both of these views at once and let the surveillance plan reflect which finding is actually on the report.

Why this matters for the patient who asked

Her report described a margin finding, and her imaging and operative findings were clean. Depending on which margin is being described, she could be in the lower-risk group the data supports for resection-edge involvement, or in the modestly elevated group the data supports for extra-appendiceal acellular mucin. Those are not interchangeable, and the difference shows up in how often she gets scanned and how long surveillance continues.

A reasonable next stepMost high-volume appendix cancer programs will offer a second pathology review for any LAMN with margin involvement, perforation, or any mention of extra-appendiceal mucin. A second read can confirm whether the mucin is truly acellular, whether it is sitting at the resection edge or on the serosal surface, whether the margin is actually involved or simply close, and whether there are subtle epithelial cells that change the picture. If a second read was not offered, asking for one gives the surveillance plan a firmer foundation, regardless of which interpretation turns out to be correct.

2. Tumor markers: CEA, CA 19-9, and CA-125

Her plan was to draw CEA and CA 19-9 now, and CA-125 alone in a year, with no scheduled repeats. That is not how most LAMN surveillance protocols are written, and it is worth understanding why.

No single tumor marker reliably tracks LAMN. Some patients elevate CEA, some CA 19-9, some CA-125, and a meaningful number elevate none of them even when there is disease. Programs that have published their criteria, including the active surveillance protocol from a 2024 expert center series, require a normal baseline across all three markers as part of their entry criteria, and then repeat all three on a defined schedule alongside imaging.

The 2025 German S2k guideline on LAMN and pseudomyxoma peritonei recommends imaging and tumor marker evaluation every six months for five years for patients in surveillance, while flagging that the underlying evidence is limited and largely consensus-based.

Drawing all three markers once and then a single marker a year later is not the way most published protocols set this up. It does not mean the care is wrong. It means the follow-up was not built from one.

3. Imaging: chest in, pelvis out

This is the part of the plan that is hardest to square with the disease.

LAMN is a peritoneal disease. When it recurs, it recurs in the abdomen and pelvis: mucinous deposits on peritoneal surfaces, in the omentum, on the ovaries, in the dependent recesses of the pelvis. That pattern is the entire reason imaging surveillance exists for this population.

Major appendix cancer programs and published surveillance protocols converge on CT or MRI of the abdomen and pelvis as the standard imaging. The German S2k guideline, the active surveillance MRI protocol, and the structured surveillance program studies all use abdominopelvic imaging. Chest imaging shows up at baseline for some high-grade or advanced disease, but it is not routinely repeated for low-grade LAMN, where pulmonary recurrence is not the dominant pattern of relapse.

A surveillance scan that includes the chest while excluding the pelvis is unusual for LAMN. If anything, the priority is reversed.

A reasonable thing to ask“Given that LAMN recurs in the peritoneum, can my imaging be CT abdomen and pelvis instead of chest and abdomen?” That is a clarifying question, not a confrontational one, and most surveillance programs will agree without difficulty.

4. The one-year gap with no plan

This is where her frustration is most justified, and where the literature is clearest.

Most published LAMN surveillance programs include some structure within the first year after surgery. The active surveillance protocol from a 2024 expert center series schedules imaging, biology, and clinical assessment at six months and then yearly. The 2025 German S2k guideline recommends six-month intervals for the first five years. The structured surveillance program that tracked progression to pseudomyxoma peritonei found that the highest risk window for progression sits in the first three years after diagnosis.

That does not mean every pT3 LAMN patient must have six-month imaging. Practice varies, and some programs do extend to annual imaging early. What is consistent across published protocols is that there is a written plan, with defined intervals, defined modalities, and at least one interim point of contact during the first year. A single referral with no intake, no instructions, and no interim touchpoint is not a structured program. It is a placeholder. She is right to read it that way.

What to actually ask for

None of this means a patient should escalate, switch centers, or assume their care is wrong. Most of these gaps are about communication and structure, not clinical judgment. A short, specific list of questions usually closes them.

• Can my pathology be sent for a second review at a high-volume appendix cancer center?
• What is the written surveillance schedule for the next 2 to 5 years, including imaging modality, body coverage, and tumor markers?
• Will my imaging include the pelvis, given that LAMN recurs peritoneally?
• Will CEA, CA 19-9, and CA-125 be drawn together at each surveillance interval?
• Is there a defined interim contact, even a virtual one, before my one-year visit?

The bottom line

She is not asking to be over-treated. She is asking for a plan she can recognize as a plan. Recurrence risk for a localized LAMN with a clean CT is genuinely low, and the published literature supports a relatively gentle surveillance schedule for this group. What that literature also supports is that the schedule should exist on paper, should cover the abdomen and pelvis, should track all three tumor markers, and should not leave a full year of silence between the end of one appointment and the beginning of the next.

Low risk is not the same as no plan. For appendix cancer patients, that distinction matters more than almost anything else, because uncertainty, more than the underlying risk, is what drihttps://form.jotform.com/Moore_Amanda_info/appendicure-patient-data-collectionves the anxiety and the missed follow-up and the avoidable progression.

And while I have you: Register Your Data Too

You can do that HERE

I said at the top I would come back to this.

This morning’s post was about the high-grade side, and why high-grade patients need to be counted in the Appendicure patient-led data registry. The case for low-grade is the same.

Look at the studies I cited above. The Mayo cohort is 125 patients. The single-institution case series is 64. The active surveillance program is 30. The structured surveillance program is in the dozens. These are the numbers we are working with when we try to say something useful about LAMN follow-up. They are small because LAMN is rare, and they are scattered because every center collects its own data its own way and most patients are never counted at all.

That is the reason her surveillance plan looks the way it does. Not because anyone is being careless. Because the evidence base is thin, and thin evidence produces patchy protocols, and patchy protocols produce five-minute follow-ups that leave patients with more questions than answers.

The Appendicure registry is patient-led, which means you do not need your center to enroll you. You enter your own data. Pathology, surgery, surveillance schedule, scans, markers, recurrences, treatment changes. Every patient who enters their data makes the next patient’s plan a little less of a guess. Low-grade patients are the ones we are most often missing, because so many of you are told some version of you are fine, see you in a year, and never end up in a study at all.

If you have a LAMN diagnosis, please consider registering. If you have already registered, please keep your record current as your surveillance unfolds. The patient who wrote the post that triggered this piece is exactly the kind of patient whose data we need: pT3, acellular mucin somewhere, clean imaging, structured questions, no clear answers from her care team. Multiply her by a few hundred and we start to be able to say something real about what surveillance for LAMN should actually look like.

The reason her plan looks like a placeholder is partly that ours is the first generation of LAMN patients with the tools to count ourselves. So count yourself!

Sources

• Lee J, et al. Risk stratification of surveillance for low-grade appendiceal mucinous neoplasms. (Mayo Clinic cohort, 2024). PubMed: pubmed.ncbi.nlm.nih.gov/39209560/
• Wong M, et al. Low-Grade Appendiceal Mucinous Neoplasms: A Single Institution Experience of 64 Cases With Clinical Follow-up.
• Active surveillance for low-grade appendiceal mucinous neoplasm. Pleura and Peritoneum, 2024. PMC10980982.
• Surveillance of low-grade appendiceal mucinous neoplasms for progression to pseudomyxoma peritonei: results from a structured surveillance programme. PMC11683163.
• Local Protocol for Management of LAMN. PMC7501353.
• Müller S, et al. German S2k-guideline on diagnostics, treatment and surveillance of low-grade appendiceal mucinous neoplasms (LAMN). European Journal of Cancer, 2025.
• College of American Pathologists Protocol for the Examination of Specimens From Patients With Carcinoma of the Appendix.

One last thing

David’s colonoscopy is Friday. He is a polyp farm. The last two times he has had fifteen-plus polyps pulled, and they keep showing up every six months like clockwork. I am hoping this round shows fewer. I have always understood that appendix cancer does not spread to the colon, and I am holding onto that quietly while we wait for results. If you pray, send some up. If you send good thoughts into the universe, those count too. I will let you know how it goes.

A note on this post This is educational, not medical advice. Surveillance decisions for LAMN belong with a clinician who knows appendix cancer, ideally at a high-volume program. If your follow-up plan does not look like what published protocols describe, the questions in this post are a starting point for that conversation, not a script to read out loud.