It's how you indicate a former site of malignancy with a Z code in ICD-10-CM.

When a site of malignancy has been removed and there’s no active treatment aimed at that location, how should we reflect that history in the medical code? The short answer is: use a Z code. More specifically, Z codes in ICD-10-CM are designed to capture factors that influence health status, including a patient’s history of cancer. It’s a simple idea with big implications for clear, honest medical records.

Let me explain what this means in practice and why it matters for clinicians and coders alike.

What are Z codes, and why do they matter?

Z codes sit in the chapter of ICD-10-CM that covers “factors influencing health status.” They aren’t about the disease itself at the moment of care; they’re about the broader context of a patient’s health. Among these, the codes that denote a history of disease are especially useful. A personal history code signals, in plain terms, that the patient had a condition in the past but is not actively being treated for it now.

Think of it this way: when cancer has been excised and there’s no current treatment directed at that site, the chart should tell future readers, “This cancer has been removed; the patient’s current health status isn’t driven by this malignancy.” That clarity helps everyone—from the primary care clinician planning follow-up to a surgeon coordinating future care to a researcher analyzing long-term outcomes.

A typical way this is coded is with a Z code that indicates a history of a malignant neoplasm. You’ll often see something like Z85.x, where the x stands in for the specific site of the cancer (for instance, Z85.3 is a historical note for breast cancer). The exact numeric depends on the site involved, but the principle is the same: personal history of cancer, not an active disease process.

Why not use a primary or secondary code here?

Primary codes are reserved for the patient’s current, active condition. If the cancer site isn’t actively being treated and there are no active cancer symptoms, a primary code for cancer would be misleading. It would imply that the malignancy is still the focus of the encounter, which isn’t the case when the site has been excised and no ongoing treatment is directed there.

Secondary codes can supplement the record when relevant ancillary conditions exist (like a complication or a comorbidity). But for a past cancer that isn’t impacting the current visit, a secondary code about the past cancer wouldn’t convey the right clinical meaning on its own. The Z code for a history of malignancy communicates a patient story: “This site has been removed; there’s no active cancer at this location.”

Not everything that isn’t active needs a Z code, though. If the visit centers on a separate, unrelated issue, the chart will reflect the active problem with its appropriate codes. The Z code for history of cancer should appear when the cancer history is clinically relevant to the current care, or when it provides essential context for ongoing surveillance or risk assessment.

Not otherwise specified (NOS) is not the right vehicle here

In ICD-10-CM, specificity is prized. An NOS code would essentially be a placeholder for “unspecified.” That’s not ideal when you’re documenting a known history that you want to flag clearly. The point here isn’t to “unspecify” but to accurately label that a malignancy was present in the past and that no active treatment is ongoing for that site. Hence, the Z code is the better, more precise choice.

Putting it into practice: what this looks like in real charts

Let’s walk through a couple of everyday scenarios to ground this idea.

Scenario 1: A patient had breast cancer, underwent lumpectomy, and there’s no active disease or current treatment directed at the breast. During a routine follow-up visit, the clinician notes “no evidence of active disease.” In the chart, the coder places a Z85.x code to reflect personal history of malignant neoplasm of the breast. The encounter can still include other codes for the visit’s current concerns, but the breast cancer history is clearly labeled as past disease.

Scenario 2: A patient completed cancer treatment and returns for a follow-up examination after completed treatment. This is where Z08 comes into play. Z08 is used for encounters specifically for follow-up after completed treatment for a malignant neoplasm. If the visit’s main purpose is surveillance after treatment, you might pair Z08 with a site-specific history code (Z85.x) to give a complete picture: “history of cancer” and “follow-up after treatment.” The exact combination will depend on the chart details and the coding guidelines you’re following, but the principle holds: one code signals past disease, another signals the follow-up context if that’s the reason for the visit.

Key tips for coders and clinicians

• Be explicit about the current status. If the cancer has been excised and there’s no active therapy, use a history code (Z85.x) to tell readers the site is not an active issue.

• Use follow-up codes when the visit is specifically for surveillance after treatment (Z08). If the visit is truly about ongoing surveillance with no direct cancer treatment plan, the Z08 code adds helpful context.

• Don’t conflate past cancer with an active condition. Keep the focus of the encounter on current health needs, and let the history code provide the backdrop.

• Check site specificity. If possible, attach the site-specific history code (Z85.x for the appropriate cancer site) to improve precision. The exact numeric code will depend on the cancer site.

• Always align with local guidelines. ICD-10-CM coding guidance and payer requirements can influence how you combine Z codes with other codes. When in doubt, review the coding guidelines for Z codes and for malignancies to ensure consistency.

A few practical examples to illustrate the idea

• Example A: The patient had a history of prostate cancer that was treated years ago with surgery. Today’s visit is for hypertension management, and there are no active cancer concerns. Coding would include a Z85.x code indicating history of malignancy of the prostate, paired with the hypertension code as the active issue.

• Example B: The patient had melanoma removed a while back and now returns for a routine follow-up imaging study. There’s no active melanoma treatment planned. The chart could reflect Z85.x for history of melanoma and, depending on the visit purpose, possibly a Z08 if the visit is specifically a follow-up after completed treatment.

• Example C: A patient with a distant history of cancer presents with a non-cancer-related complaint, such as a skin infection. You’d still include the cancer history code to acknowledge it in the record, but the active issue on this encounter is the infection, coded accordingly.

Maintaining clarity and consistency

The beauty of using Z codes for cancer history is in the clarity they bring. Medical records are navigated by teams across specialties and time. A surgeon, a primary care physician, a nurse practitioner, or a coder—their common thread is understanding the patient’s current health in the context of what came before. A Z code for history of malignancy acts like a bookmark in the chart, signaling, “This has happened, but it isn’t the active problem right now.”

As you work with these codes, you’ll start to notice that the practice of documenting history isn’t about piling on every old diagnosis. It’s about telling a concise, accurate story that helps future care plans be safer and smarter. And yes, this matters in everyday care, not just in theoretical tests or textbooks.

A quick recap

• When a former site of malignancy has been excised and there’s no current treatment aimed at that site, a Z code is used to indicate the history of cancer.

• Z codes capture health status factors, including a patient’s cancer history, helping other clinicians understand what is active and what has been resolved.

• The primary code should reflect current active problems; a history code (Z85.x) tells the story of past cancer. If the visit is specifically for follow-up after completed cancer treatment, Z08 may be appropriate.

• Avoid using NOS for this purpose; specificity matters.

Final thought

Medical coding isn’t just about ticking boxes. It’s about clear communication across teams, time, and settings. A former site of malignancy, once excised and no longer treated, deserves to be documented honestly and precisely. Using a Z code to reflect that history ensures the chart communicates the true state of the patient, supports appropriate follow-up, and reduces confusion down the line. If you remember one thing, let it be this: history matters, and Z codes are their quiet, precise voice in the chart.