Cancer of unknown primary, unfavourable: the decisions you may face
5 treatment settings, 4 with more than one named option. Each section lays out the options the standard of care names, what each is for, the trials behind them with their recorded results, the side effects and cautions on record, and questions to ask. Built from the cancer page's standard-of-care rows; nothing here is advice for your case.
Exclude favourable subsets; comprehensive genomic profiling of tissue or plasma; assess performance status and lactate dehydrogenase.
Histopathology means looking at cancer cells under a microscope, and immunohistochemistry stains them for specific proteins. Together they are still the foundation of every diagnosis.
- Cheap, fast, universal
- Companion diagnostic for most targeted drugs
Sequencing hundreds of cancer genes at once from a biopsy to find the mutations a drug can target.
- One test, all actionable alterations
- Trial matching
A blood test that reads fragments of DNA shed by the tumour, so you can genotype or monitor cancer without a needle in the tumour.
- Minimally invasive, repeatable
- Whole-body clonal picture
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- Subjective scoring
- Single-site sampling misses heterogeneity
- Tissue quantity
- VUS interpretation
- 2-3 week turnaround
- Low shedding in some tumours (brain, early-stage)
- Clonal haematopoiesis false positives
- Between Histopathology & immunohistochemistry, Comprehensive genomic profiling and Liquid biopsy (ctDNA), which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (ESMO Clinical Practice Guideline on cancer of unknown primary 2023), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (work-up), which of the standard options do you recommend and why?Why: Guideline options include: Exclude favourable subsets; comprehensive genomic profiling of tissue or plasma; assess performance status and lactate dehydrogenase.
Add these to your appointment list, or take the full question set for this cancer.
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 is a platinum chemotherapy that crosslinks DNA; it is part of the standard pre-surgery regimen for triple-negative breast cancer.
A microtubule poison discovered in the Pacific yew tree, among the most used chemotherapies in breast, lung, and ovarian cancer.
Gemcitabine plus cisplatin has been the chemotherapy backbone for bile duct cancer since 2010 and is now given with immunotherapy.
Platinum agents such as cisplatin and carboplatin work by crosslinking DNA. They are curative in testicular cancer and central to lung, ovarian, bladder, head and neck, and TNBC treatment.
- Broad activity
- Synergy with HRD
- Newly diagnosed unfavourable cancer of unknown primary controlled by three cycles of platinum chemotherapy: randomised to molecularly guided therapy chosen from tissue and blood genomic profiling, or to continued chemotherapy
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- Median progression-free survival 6.1 months with molecularly guided therapy versus 4.4 months with continued chemotherapy (hazard ratio 0.72); overall survival immature.
Progression-free survival (months): Molecularly guided therapy 6.1 vs Continued chemotherapy 4.4 · HR 0.72 · source
- Dose by Calvert formula using GFR (see the calculators).
- Nephro-, oto-, neurotoxicity
- Between Carboplatin, Paclitaxel / nab-paclitaxel, Gemcitabine + cisplatin and the other options, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in CUPISCO, and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (ESMO Clinical Practice Guideline on cancer of unknown primary 2023), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (first line, fit patients), which of the standard options do you recommend and why?Why: Guideline options include: 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).
- Am I a candidate for Carboplatin, Paclitaxel / nab-paclitaxel, Gemcitabine + cisplatin, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of CUPISCO apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.
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 is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Nivolumab was the second PD-1 blocker and is often combined with ipilimumab. Long-term data show about half of advanced melanoma patients alive at 10 years on the combination.
Sequencing hundreds of cancer genes at once from a biopsy to find the mutations a drug can target.
- One test, all actionable alterations
- Trial matching
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Colitis with ipilimumab (1+3 mg/kg) · Monotherapy pooled unless stated | 25% | 14.4% |
| Hepatitis with ipilimumab · Monotherapy pooled unless stated | 15% | 13.4% |
| Colitis · Monotherapy pooled unless stated | 2.9% | 1.7% |
| Hepatitis · Monotherapy pooled unless stated | 1.8% | 1.5% |
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Tissue quantity
- VUS interpretation
- 2-3 week turnaround
- Between Pembrolizumab, Nivolumab and Comprehensive genomic profiling, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- Which side effects of Pembrolizumab or Nivolumab are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (ESMO Clinical Practice Guideline on cancer of unknown primary 2023), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (actionable alterations), which of the standard options do you recommend and why?Why: Guideline options include: Tumour-agnostic therapies: pembrolizumab or nivolumab for MSI-high or high tumour mutational burden, NTRK inhibitors, BRAF and MEK inhibitors, HER2-directed therapy.
- Am I a candidate for Pembrolizumab, Nivolumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
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 was the second PD-1 blocker and is often combined with ipilimumab. Long-term data show about half of advanced melanoma patients alive at 10 years on the combination.
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
- A Phase II/III Study of F520 Combined With Paclitaxel Plus Carboplatin in the Treatment of Cancer of Unknown Primary (CUP)Phase 2/3NCT07761429402 peopleevidence 35A Multicenter, Randomized, Double-blind, Placebo-controlled Phase II/III Study Evaluating the Safety and Efficacy of F520 Combined With Paclitaxel Plus Carboplatin as First-line Treatment for Cancer of Unknown Primary
No headline result recorded yet.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Colitis with ipilimumab (1+3 mg/kg) · Monotherapy pooled unless stated | 25% | 14.4% |
| Hepatitis with ipilimumab · Monotherapy pooled unless stated | 15% | 13.4% |
| Colitis · Monotherapy pooled unless stated | 2.9% | 1.7% |
| Hepatitis · Monotherapy pooled unless stated | 1.8% | 1.5% |
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Between Nivolumab and Pembrolizumab, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in A Phase II/III Study of F520 Combined With Paclitaxel Plus Carboplatin in the Treatment of Cancer of Unknown Primary (CUP), and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- Which side effects of Nivolumab or Pembrolizumab are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (ESMO Clinical Practice Guideline on cancer of unknown primary 2023), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (second line), which of the standard options do you recommend and why?Why: Guideline options include: Alternative chemotherapy, PD-1 antibody if not given (nivolumab approved in Japan), or trial entry; trials of antibody-drug conjugates and immunotherapy combinations.
- Am I a candidate for Nivolumab, Pembrolizumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of A Phase II/III Study of F520 Combined With Paclitaxel Plus Carboplatin in the Treatment of Cancer of Unknown Primary (CUP) apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.
Poor performance status
Best supportive care with early palliative care involvement.
This setting names no product or technology record yet; the approach above is the standard as written. Ask your team which specific treatments they mean.
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
No side-effect rates or interaction flags are recorded for these options yet. The side-effect lookup and interaction checker cover the products that have them.
- Which specific treatments are you proposing for this setting, and what are the alternatives?Why: The standard of care here is described in words rather than named products; ask for the names.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (ESMO Clinical Practice Guideline on cancer of unknown primary 2023), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (poor performance status), which of the standard options do you recommend and why?Why: Guideline options include: Best supportive care with early palliative care involvement.
Add these to your appointment list, or take the full question set for this cancer.