Cancer of unknown primary origin
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]
Synonyms and keywords: Occult cancer; CUP; Metastases of unknown primary origin; Unknown primary origin neoplasm; Cancers of unknown primary site; Neoplasms of unknown primary site; Carcinoma of Unknown Primary
Overview
Cancer of unknown primary origin is the diagnosis of metastatic cancer when the anatomic site of origin remains unidentified. Cancer of unknown primary origin is common, and it accounts for 3–5% of all cancers. Cancer of unknown primary origin may be classified according to pathology findings into 5 groups: well and moderately differentiated adenocarcinomas, poorly differentiated carcinomas, squamous cell carcinomas, undifferentiated neoplasms, and carcinomas with neuroendocrine differentiation. The treatment for cancer of unknown primary origin will depend on several factors, such as: metastatic origin, biopsy findings, patients age, and performance status.
Historical Perspective
- Cancer of unknown primary origin was first described in 1980.
- In 1980 to 1990, the definition of unknown primary cancer was based on imaging results.
Classification
- Cancer of unknown primary origin may be classified according to pathology findings into 5 groups:
- Well and moderately differentiated adenocarcinomas
- Poorly differentiated carcinomas
- Squamous cell carcinomas
- Undifferentiated neoplasms
- Carcinomas with neuroendocrine differentiation
Pathophysiology
- The pathogenesis of cancer of unknown primary origin is characterized by [feature1], [feature2], and [feature3].
- The [gene name] gene/Mutation in [gene name] has been associated with the development of cancer of unknown primary origin, involving the [molecular pathway] pathway.
- On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of Cancer of unknown primary origin.
- On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of Cancer of unknown primary origin.
Causes
- Cancer of unknown primary origin may be caused by either [cause1], [cause2], or [cause3].
- Cancer of unknown primary origin is caused by a mutation in the [gene1], [gene2], or [gene3] gene[s].
- There are no established causes for cancer of unknown primary origin.
Differentiating Cancer of Unknown Primary Origin from Other Diseases
- Cancer of unknown primary origin must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as:
- Incidentaloma
- [Differential dx2]
- [Differential dx3]
Epidemiology and Demographics
- The prevalence of cancer of unknown primary origin is approximately [number or range] per 100,000 individuals worldwide.
- In [year], the incidence of Cancer of unknown primary origin was estimated to be [number or range] cases per 100,000 individuals in [location].
Age
- Patients of all age groups may develop cancer of unknown primary origin.
- Cancer of unknown primary origin is more commonly observed among patients aged [age range] years old.
- Cancer of unknown primary origin is more commonly observed among [elderly patients/young patients/children].
Gender
- Cancer of unknown primary origin affects men and women equally.
- [Gender 1] are more commonly affected with cancer of unknown primary origin than [gender 2].
- The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.
Race
- There is no racial predilection for cancer of unknown primary origin.
- Cancer of unknown primary origin usually affects individuals of the [race 1] race.
- [Race 2] individuals are less likely to develop Cancer of unknown primary origin.
Risk Factors
- Common risk factors in the development of cancer of unknown primary origin are [risk factor 1], [risk factor 2], [risk factor 3], and [risk factor 4].
Natural History, Complications and Prognosis
- The majority of patients with cancer of unknown primary origin remain asymptomatic for [duration/years].
- Early clinical features include [manifestation 1], [manifestation 2], and [manifestation 3].
- If left untreated, [#%] of patients with Cancer of unknown primary origin may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].
- Common complications of Cancer of unknown primary origin include [complication 1], [complication 2], and [complication 3].
- Prognosis is generally poor , and the 5 mortality rate of patients with cancer of unknown primary origin is approximately .
Diagnosis
Diagnostic Criteria
- The diagnosis of cancer of unknown primary origin is made when at least [number] of the following [number] diagnostic criteria are met:
- [criterion 1]
- [criterion 2]
- [criterion 3]
- [criterion 4]
Symptoms
- Cancer of unknown primary origin may be asymptomatic.
- Symptoms of cancer of unknown primary origin may include the following:
- [symptom 1]
- [symptom 2]
- [symptom 3]
- [symptom 4]
- [symptom 5]
- [symptom 6]
Physical Examination
- Patients with cancer of unknown primary origin usually appear [general appearance].
- Physical examination may be remarkable for:
- [finding 1]
- [finding 2]
- [finding 3]
- [finding 4]
- [finding 5]
- [finding 6]
Laboratory Findings
- Laboratory findings associated with cancer of unknown primary origin, may include:
- Elevated levels of carcinoembryonic antigen
- Elevated levels cancer antigen 125
- Elevated levels cancer antigen 19-9
- Elevated levels cancer antigen 27.29
Imaging Findings
- There are no [imaging study] findings associated with cancer of unknown primary origin.
- [Imaging study 1] is the imaging modality of choice for cancer of unknown primary origin.
- On [imaging study 1], Cancer of unknown primary origin is characterized by [finding 1], [finding 2], and [finding 3].
- [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].
Other Diagnostic Studies
- Cancer of unknown primary origin may also be diagnosed using [diagnostic study name].
- Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].
Treatment
Medical Therapy
- There is no treatment for cancer of unknown primary origin; the mainstay of therapy is supportive care.
- The table below summarizes the mainstay of therapy for cancer of unknown primary origin.
| Treatment for cancer of unknown primary origin Adapted from the European Society of Oncology | |
|---|---|
| Sub-type | Proposed treatment |
|
Poorly differentiated carcinoma, predominately nodal disease |
Platinum based combination chemotherapy |
|
Peritoneal carcinomatosis in female |
Platinum based chemotherapy |
|
Isolated axillary nodal metastases in female |
Identical to breast cancer with similar nodal involvement |
|
Squamous carcinoma of cervical lymph nodes |
Irradiation for N1-N2 disease. |
|
Liver, bone or multiple-site metastases of adenocarcinoma |
Low toxicity chemotherapy of palliative orientation or best supportive care are acceptable |
Surgery
- Surgery is the mainstay of therapy for cancer of unknown primary origin.
- [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of Cancer of unknown primary origin.
- [Surgical procedure] can only be performed for patients with [disease stage] Cancer of unknown primary origin.
Prevention
- There are no primary preventive measures available for cancer of unknown primary origin.