# Cancer of unknown primary, unfavourable (adenocarcinoma and poorly differentiated carcinoma)

Source: https://onco.cc/cancers/cup-unfavourable/  
OnCo record `cup-unfavourable` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Unfavourable cancer of unknown primary is the large majority of cases, where a metastatic adenocarcinoma or poorly differentiated carcinoma fits no recognised pattern and its origin cannot be found. Treatment has long been general-purpose platinum chemotherapy, but CUPISCO showed that matching drugs to the tumour's genetic faults after short chemotherapy holds the disease longer.

## Summary

Most patients with cancer of unknown primary do not fit a favourable subset. They have adenocarcinoma or poorly differentiated carcinoma in the liver, lungs, bones or several sites at once, are often unwell at diagnosis, and survival is short; performance status and serum lactate dehydrogenase are the strongest predictors of survival. For thirty years treatment has been empirical: carboplatin with paclitaxel or gemcitabine with cisplatin, regimens chosen because they work across many cancers, with response rates around a third and median survival of about nine to twelve months in trial populations and shorter in the clinic. Randomised trials of classifier-directed site-specific chemotherapy (GEFCAPI 04, Lancet Oncology 2019, and a Japanese trial) did not improve on this, and PD-1 antibodies produced responses in about a fifth of patients in the NivoCUP trial (Annals of Oncology 2022) and the CUPISCO immunotherapy arm, leading to nivolumab's approval for CUP in Japan in 2021.

The CUPISCO trial (Lancet 2024) changed the framing. After three cycles of platinum-based induction chemotherapy, 636 patients with unfavourable CUP whose disease had not progressed were randomised to continue chemotherapy or to switch to molecularly guided therapy chosen by a tumour board from comprehensive genomic profiling, including targeted drugs for actionable alterations and atezolizumab for tumours with high mutational burden or without a target: progression-free survival rose from 4.4 to 6.1 months, a modest but real gain that established genomic profiling as part of the standard work-up. About a third of patients carry an actionable alteration (HER2, BRAF V600E, NTRK fusions, MSI or high tumour mutational burden, and others), and the ESMO 2023 guideline recommends profiling for all patients fit for treatment; circulating tumour DNA is an alternative when tissue is scarce. Trials now test targeted agents, immunotherapy combinations and antibody-drug conjugates with chemotherapy in first line, and DNA-methylation classifiers are being revisited as a route to site-specific immunotherapy choices. Early palliative care and honest discussion of prognosis are part of standard management.

## Fields

- Kind: Cancer
- Last checked: 2026-09-18
- Also known as: Unfavourable-risk CUP; Poor-prognosis CUP; CUP adenocarcinoma with liver or multiple metastases; Non-specific CUP
- Tags: subtype-page; site-agnostic
- Group: other
- Burden: About four fifths of cancers of unknown primary; most are adenocarcinomas or poorly differentiated carcinomas with liver, lung, bone or multiple metastases, and median survival on empirical chemotherapy is under a year.
- Subtypes: Adenocarcinoma of unknown primary with liver metastases; Adenocarcinoma of unknown primary with multiple metastatic sites; Poorly differentiated carcinoma of unknown primary (non-midline, marker negative); Squamous cell carcinoma of unknown primary at non-nodal sites; Cancer of unknown primary with an actionable alteration (HER2, BRAF, NTRK, MSI-high, high tumour mutational burden); Cancer of unknown primary with poor performance status (best supportive care)
- Biomarkers: Comprehensive genomic profiling (actionable alterations in about a third); Microsatellite instability, tumour mutational burden and PD-L1 (immunotherapy); Performance status and serum lactate dehydrogenase (prognosis); Immunohistochemistry lineage panel (to exclude favourable subsets); Circulating tumour DNA where tissue is insufficient; Tissue-of-origin classifier (supportive)

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/cup-unfavourable/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/cup-unfavourable/#overview [3 state-of-the-art points]
- Types and stages (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/cup-unfavourable/#what-it-is [6 subtypes]
- Symptoms and diagnosis (on the hub): How this cancer shows itself, how the diagnosis is confirmed, and the biomarkers clinicians test for. https://onco.cc/cancers/cup-unfavourable/#finding-it [6 biomarkers]
- Treatment (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/cup-unfavourable/#treating-it [5 settings, 4 decisions with options]
- Trials and papers (on the hub): Trials recruiting now, the landmark trials, the trials held by this cancer's subtypes, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/cup-unfavourable/#evidence [2 trials, 3 key papers, 5 milestones]
- Biology and targets (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/cup-unfavourable/#science [4 targets]
- Countries and centres (own page): Cases by country, the UK and NHS pathway and other country lenses, the expert centres with trials on record, and the centres named on this cancer's subtypes. https://onco.cc/cancers/cup-unfavourable/where-you-are/
- Decisions and support (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/cup-unfavourable/#living-with-it [19 questions, 6 red cards]
- Pipeline and open problems (own page): Everything in development, the medicines held by this cancer's subtypes, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/cup-unfavourable/coming/ [5 medicines, 2 trials, 4 open problems]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/cup-unfavourable/data/ [31 connected records]

## Standard of care

- Work-up: Exclude favourable subsets; comprehensive genomic profiling of tissue or plasma; assess performance status and lactate dehydrogenase. ([Histopathology & immunohistochemistry](https://onco.cc/technologies/histopathology-ihc/), [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/), [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/), [Tumour-agnostic (tissue-agnostic) approval](https://onco.cc/terms/tumour-agnostic/))
- First line, fit patients: Platinum-based doublet (carboplatin-paclitaxel or gemcitabine-cisplatin) for three cycles, then continuation or a switch to molecularly guided therapy where an actionable alteration is found (CUPISCO). ([Carboplatin](https://onco.cc/drugs/carboplatin/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Gemcitabine + cisplatin](https://onco.cc/drugs/gemcitabine-cisplatin/), [CUPISCO](https://onco.cc/trials/cupisco/), [Platinum agents](https://onco.cc/technologies/platinum/))
- Actionable alterations: Tumour-agnostic therapies: pembrolizumab or nivolumab for MSI-high or high tumour mutational burden, NTRK inhibitors, BRAF and MEK inhibitors, HER2-directed therapy. ([Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Tumour-agnostic (tissue-agnostic) approval](https://onco.cc/terms/tumour-agnostic/), [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/))
- Second line: Alternative chemotherapy, PD-1 antibody if not given (nivolumab approved in Japan), or trial entry; trials of antibody-drug conjugates and immunotherapy combinations. ([Nivolumab](https://onco.cc/drugs/nivolumab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [A Phase II/III Study of F520 Combined With Paclitaxel Plus Carboplatin in the Treatment of Cancer of Unknown Primary (CUP)](https://onco.cc/trials/nct07761429/))
- Poor performance status: Best supportive care with early palliative care involvement. ([Pain relief and palliative care are unavailable to most](https://onco.cc/bottlenecks/b-palliative/))

## State of the art

- CUPISCO is the first randomised trial to show a benefit from genomically guided therapy in this disease.
- Comprehensive genomic profiling is now recommended for all fit patients.
- Immunotherapy produces durable responses in a minority and is approved in Japan.

## Open problems

- Median survival remains under a year for most patients.
- Only a third have an actionable alteration and the gain from targeting it is modest.
- Patients too unwell for CUPISCO-style induction have no evidence-based option.
- The disease is under-studied because it belongs to no organ-based specialty.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Cancer_of_unknown_primary_origin
- CUPISCO (Lancet 2024): https://doi.org/10.1016/S0140-6736(24)00814-6
- ESMO CUP guideline 2023: https://doi.org/10.1016/j.annonc.2022.11.013
- Wikipedia: https://en.wikipedia.org/wiki/Cancer_of_unknown_primary_origin

## Connected records

- cancers: [Cancer of unknown primary (CUP)](https://onco.cc/cancers/cancer-of-unknown-primary/), [Cancer of unknown primary, favourable subsets](https://onco.cc/cancers/cup-favourable-subsets/), [Metastatic cancer (cancer that has spread)](https://onco.cc/cancers/metastatic-cancer/)
- technologies: [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/), [DNA methylation profiling](https://onco.cc/technologies/methylation-profiling/), [Histopathology & immunohistochemistry](https://onco.cc/technologies/histopathology-ihc/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/), [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/), [PET/CT](https://onco.cc/technologies/pet-ct/), [Platinum agents](https://onco.cc/technologies/platinum/)
- targets: [BRAF](https://onco.cc/targets/braf/), [HER2](https://onco.cc/targets/her2/), [NTRK](https://onco.cc/targets/ntrk/), [PD-1](https://onco.cc/targets/pd1/)
- drugs: [Carboplatin](https://onco.cc/drugs/carboplatin/), [Gemcitabine + cisplatin](https://onco.cc/drugs/gemcitabine-cisplatin/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- terms: [Immunohistochemistry (IHC)](https://onco.cc/terms/ihc/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/), [Primary tumour](https://onco.cc/terms/primary-tumour/), [Tumour mutational burden (TMB)](https://onco.cc/terms/tmb/), [Tumour-agnostic (tissue-agnostic) approval](https://onco.cc/terms/tumour-agnostic/)
- trials: [A Phase II/III Study of F520 Combined With Paclitaxel Plus Carboplatin in the Treatment of Cancer of Unknown Primary (CUP)](https://onco.cc/trials/nct07761429/), [CUPISCO](https://onco.cc/trials/cupisco/)
- key papers: [Cancer of unknown primary: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up](https://onco.cc/key-papers/paper-esmo-cancer-of-unknown-primary-guideline-ann-oncol-2023/), [CUPISCO: molecularly guided therapy versus chemotherapy after disease control in unfavourable cancer of unknown primary](https://onco.cc/key-papers/paper-cupisco-molecularly-guided-therapy-cup-lancet-2024/), [Randomised phase 2 trial of site-specific treatment based on gene expression profiling versus carboplatin and paclitaxel in cancer of unknown primary](https://onco.cc/key-papers/paper-hayashi-site-specific-vs-empirical-chemotherapy-cup-jco-2019/)
- bottlenecks: [Pain relief and palliative care are unavailable to most](https://onco.cc/bottlenecks/b-palliative/)

---
JSON: https://onco.cc/api/v1/entities/cup-unfavourable.json