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Medical Oncology Vol. I, Case 0017 — Breast Cancer

Watching Instead of Treating: A Retired Navy Nurse Asks Why That's Even an Option

Low-grade DCIS has never reliably been shown to become invasive if left alone, and two ongoing randomized trials are actively testing whether active surveillance is a genuine, safe alternative to the surgery and endocrine therapy she has already been offered. She wants to know why anyone would experiment with her diagnosis instead of just treating it.

Abbreviations, terms, and other agents mentioned in this case DCIS — ductal carcinoma in situ  ·  COMET — a randomized trial comparing active surveillance to standard treatment in low-risk DCIS  ·  LORIS — a randomized trial of active surveillance versus surgery in low-risk DCIS  ·  ER — estrogen receptor
Presentation

Patricia H., a retired Navy nurse who spent twenty-seven years on the other side of exactly these conversations, brought a clinician's directness to her own diagnosis: low-grade, ER-positive DCIS found on a routine screening mammogram, no invasive component on core biopsy, no family history, no prior breast abnormality of any kind. Her first question to the breast surgeon wasn't about margins or radiation — it was why active surveillance was even being mentioned as an option for a cancer diagnosis, a word she'd spent a career treating as something you removed, not something you watched.

The honest answer is that DCIS occupies a genuinely unusual place in oncology: it is, by definition, a proliferation of malignant-appearing cells confined entirely within the duct, with no established, reliable evidence that low-grade DCIS specifically progresses to invasive cancer within any predictable timeframe if left untreated — a real uncertainty that has existed since population-level mammographic screening began detecting far more DCIS than autopsy studies of women who died of unrelated causes would predict should exist, implying a real population of DCIS that was never destined to become clinically significant. Two ongoing randomized trials, COMET in the United States and LORIS in the United Kingdom, are directly testing whether active surveillance is a safe alternative to standard excision, sometimes with adjuvant radiation and endocrine therapy, specifically in patients like Patricia — low-grade, hormone-receptor-positive, no invasive component — because the honest clinical answer right now is that nobody yet knows the true natural history well enough to say with confidence that surgery is preventing progression that would otherwise have happened, versus removing tissue that would have stayed indolent regardless. Her own instinct that a cancer diagnosis calls for removal isn't wrong as a general principle; it's that low-grade DCIS is one of the few diagnoses in oncology where the field itself is still actively testing whether that instinct holds.

Patricia H. · 63 New diagnosis, screening-detected
Presentation
Screening mammogram, calcifications, no palpable mass
Pathology
Low-grade DCIS, ER-positive, no invasive component on core biopsy
Extent
1.4cm on imaging, single focus
Family history
None
Occupation
Retired Navy nurse, 27 years of service
History
No prior breast biopsies or atypia

Breast surgical oncology, informed decision-making

Breast Surgical Oncologist Opening

I want to offer her the full honest picture rather than default to surgery just because it's the more familiar path: standard excision with sentinel margins remains very low-risk and highly effective, but COMET and LORIS exist precisely because the field doesn't have confident evidence that every low-grade DCIS needs that intervention to prevent a future invasive cancer.

Radiation Oncologist Response

I'd frame the uncertainty slightly differently for her: even within the surveillance trials, patients are still followed with intensive imaging, not simply left alone, so "active surveillance" isn't the absence of medical attention — it's a genuinely different intensity of intervention, not a lesser one in terms of monitoring burden.

Clinical Pharmacologist Final

One piece worth naming plainly, since it applies regardless of which path she chooses: her ER-positive status means endocrine therapy, tamoxifen or anastrozole, is a real option either as a surveillance-arm risk-reduction strategy or as standard adjuvant therapy after excision — the DCIS-versus-surveillance decision and the endocrine-therapy decision are actually two separate questions, not one bundled choice, and she's entitled to weigh them independently rather than as a package deal.

Regimen selected
Standard Excision with Sentinel Evaluation
Surgical, not pharmacologic · If treatment pathway chosen
The established, familiar standard for DCIS, effective and low-risk, though its added benefit over surveillance in genuinely low-grade disease remains actively unproven.
Active Surveillance (COMET/LORIS Protocol)
Monitoring pathway · If surveillance chosen
Intensive imaging follow-up rather than immediate excision, directly testing whether low-grade DCIS requires intervention to prevent invasive progression.
Tamoxifen or Anastrozole
Selective Estrogen Receptor Modulator / Aromatase Inhibitor · Available under either pathway
A genuinely separate decision from the surgery-versus-surveillance question, usable for risk reduction regardless of which pathway she selects.
Where this was left

Not resolved by the end of the visit, deliberately: Patricia asked for time to think rather than decide that day, and the team agreed that both surgical excision and enrollment in an active-surveillance protocol remain genuinely reasonable options for her specific disease, with no clinical urgency pushing toward either one before her next visit.

Educational content only — a composite teaching case, not a real patient encounter or a substitute for clinical guidance. About These Cases →