How this instrument works
This calculator applies two separate classification systems to the same patient findings in metastatic hormone-sensitive prostate cancer: CHAARTED's 'high-volume' definition and LATITUDE's 'high-risk' definition. CHAARTED (Sweeney and colleagues, New England Journal of Medicine, 2015) defines high-volume disease as the presence of visceral metastases, or four or more bone lesions with at least one located beyond the vertebral bodies and pelvis. LATITUDE (Fizazi and colleagues, New England Journal of Medicine, 2017) defines high-risk disease as meeting at least two of three criteria: a Gleason score of 8 or higher, three or more bone lesions, and measurable visceral metastasis that isn't limited to lymph nodes.
These are two different classification systems, not one system with two names. CHAARTED and LATITUDE were each built around a specific clinical trial: CHAARTED tested adding docetaxel chemotherapy to standard hormone therapy, and LATITUDE tested adding abiraterone plus prednisone to standard hormone therapy. Each trial's investigators defined their own criteria for identifying patients likely to benefit most from that particular treatment intensification, using different bone-lesion thresholds (four versus three) and different combinations of criteria (an either/or rule for CHAARTED versus a count-based ≥2-of-3 rule for LATITUDE).
Because the two systems use different thresholds, they don't always classify the same patient the same way. A patient can be CHAARTED high-volume without being LATITUDE high-risk, and in principle the reverse can also occur, depending on which specific findings are present. This calculator reports both classifications side by side rather than trying to reconcile them into a single number, because that disagreement is a real feature of how the two trials were designed, not a calculation error.
This is a clinical and oncology reference tool intended to support treatment-planning discussions with an oncologist, not a patient self-diagnosis instrument. It reproduces the published trial-eligibility arithmetic on the findings entered; it does not review imaging directly, weigh comorbidities, or account for other factors an oncologist would consider when deciding whether to intensify treatment.
- Set 'Visceral metastases present' to Yes if imaging shows metastases to a visceral organ such as liver or lung — this alone satisfies CHAARTED's high-volume definition.
- Set '4 or more bone lesions' and 'At least 1 bone lesion beyond the vertebral bodies and pelvis' to Yes together to satisfy CHAARTED's other high-volume pathway — both must be Yes.
- Set 'Gleason score ≥ 8' to Yes if the biopsy Gleason score is 8 or higher — one of LATITUDE's three criteria.
- Set '3 or more bone lesions' to Yes if three or more bone metastases are present — LATITUDE's own bone-lesion threshold, lower than CHAARTED's four-lesion cutoff.
- Set 'Measurable visceral metastasis (excluding lymph nodes)' to Yes for measurable visceral disease that isn't limited to lymph nodes — LATITUDE's third criterion.
- Read the CHAARTED high-volume result, the count of LATITUDE criteria met out of 3, and whether that count reaches LATITUDE's ≥2-of-3 high-risk threshold.
Worked example — three metastatic profiles
A patient with visceral metastases, a Gleason score of 8, and measurable visceral disease excluding lymph nodes is CHAARTED high-volume on the visceral-metastasis criterion alone, and meets 2 of LATITUDE's 3 criteria (Gleason ≥8 and measurable visceral mets), crossing LATITUDE's ≥2-of-3 threshold for high-risk too — both classifications agree on this case.
A patient with four or more bone lesions, at least one beyond the vertebral bodies and pelvis, and three or more bone lesions overall, but no visceral metastases and a Gleason score under 8, is CHAARTED high-volume through the bone-lesion pathway alone — yet meets only 1 of LATITUDE's 3 criteria (three or more bone lesions), short of the 2-of-3 threshold, so LATITUDE does not classify this same case as high-risk.
A patient with none of the six findings present — no visceral metastases, fewer than four bone lesions, no lesion beyond the vertebral bodies and pelvis, a Gleason score under 8, fewer than three bone lesions, and no measurable visceral disease — is CHAARTED low-volume and meets 0 of LATITUDE's 3 criteria, well short of high-risk on either system.
Questions
Why does this calculator give two different classifications for the same patient?
CHAARTED and LATITUDE are separate classification systems built around two different clinical trials, each with its own criteria for selecting patients likely to benefit from adding a particular treatment to standard hormone therapy. They weren't designed to agree with each other, so this calculator reports both results side by side rather than merging them into one number.
What's the actual difference between CHAARTED's and LATITUDE's criteria?
CHAARTED calls disease high-volume if visceral metastases are present, or if there are four or more bone lesions with at least one beyond the vertebral bodies and pelvis. LATITUDE calls disease high-risk if at least two of three criteria are met: Gleason score 8 or higher, three or more bone lesions, or measurable visceral metastasis excluding lymph nodes. The bone-lesion thresholds (four versus three) and the combination rules (either/or versus a 2-of-3 count) are both different.
Can CHAARTED and LATITUDE really disagree on the same patient?
Yes. A patient with four or more bone lesions including at least one beyond the vertebral bodies and pelvis, but with a Gleason score under 8, no visceral metastases, and no measurable visceral disease, is CHAARTED high-volume through the bone-lesion pathway but meets only one of LATITUDE's three criteria — short of LATITUDE's threshold for high-risk. This isn't a bug; it reflects the two systems being built from different trial-eligibility rules.
What are these classifications actually used for?
Both were developed to identify which patients with newly diagnosed metastatic hormone-sensitive prostate cancer were studied when adding a second treatment to standard hormone therapy — docetaxel chemotherapy in the CHAARTED trial, abiraterone plus prednisone in the LATITUDE trial. Oncologists reference these definitions when discussing whether to intensify initial treatment beyond hormone therapy alone.
What counts as a visceral metastasis for this calculator?
A visceral metastasis is spread to an internal organ such as the liver or lung, as distinct from spread limited to bone or lymph nodes. LATITUDE's third criterion specifically requires that visceral disease be measurable and not limited to lymph node involvement, which is why the calculator asks about measurable visceral disease separately from visceral metastases in general.
Does this tool replace an oncologist's staging workup?
No. It reproduces the published CHAARTED and LATITUDE eligibility arithmetic on the findings entered; it doesn't review imaging, pathology, or other clinical context directly. Treatment decisions about intensifying hormone therapy should be made with an oncologist who can weigh these classifications alongside the full clinical picture.
References
- Sweeney CJ, et al. — Chemohormonal Therapy (CHAARTED), N Engl J Med. 2015;373(8):737-746
- Fizazi K, et al. — Abiraterone in Metastatic, Castration-Sensitive Disease (LATITUDE), NEJM. 2017;377(4):352-360
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.