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Secondary malignancy from an unknown primary site |
Table of Contents
Natural history
Prognostic factors
Management
Cure possible
Effective palliation
Hormonal treatment
Notes from the lecture delivered to the Third Annual Symposium
on Palliative Medicine RPAH 1994.
Definition: The definition of this condition has varied from one
study to another. In some studies it refers to the situation where the primary
tumour site is still unknown at autopsy. For the purpose of this discussion,
however, we will define it as a biopsy proven cancer which is inconsistent
with a primary tumour at that site, but where the primary site remains occult
despite thorough history, physical examination and appropriate additional
investigations.
Aetiology: This condition may occur in tumours which have a tendency
to metastasise early. In 15-25% of cases where the primary remains occult
during the patient's life, it is not able to be found at autopsy. In this
situation it may be that the primary has disappeared, or it may be that
the tools we have at our disposal to find it are not adequate. The primary
may have been removed or may have sloughed off skin or mucosa.
Incidence: The lifetime risk of having cancer with an unknown primary
(CUP) in NSW is : for males 1:56; for females 1:77. In Australia it is the
fourth most common cause of cancer death in males and the third most common
in females.
Histology: There is a range of histological types:
Frequency of histological subtypes of cancer of unknown primary site:
| Adenocarcinoma | 22336
| | Carcinoma | 11318 |
| Undifferentiated carcinoma | 16 | |
| SCF | 6 | 4 | |
| Low cervical | 3 | 5 | |
| Ingiunal | 3 | 1 | |
| Sub-total | 13 | 26 | 39 | | Skin
and subcutaneous | 1 | 0 | 1 | | Total | 143 | 143 | 286 |
From Kirsten, Chung, Leary, Ng, Hedley & Tattersall, 1987
When the presentation is with axillary lymph node involvement, the prognosis
in women is better overall. These patients are treated as if the primary
were breast. Mammography is negative in 50% of these cases. Other primary
sites should also be considered, eg ovary and lung.
Weight loss is a prominent sign in about 35% of all cases.
Where the presentation is with liver secondaries, one cannot assume that
the primary is in the gastro intestinal tract. Only 60% of these tumours
are adenocarcinoma. At biopsy, which should be the first investigation,
they may also be carcinoid or small cell.
Natural History:
Prognosis is generally poor with median survival of three to four months.
Fewer than 25% of patients survive a year and fewer than 10% survive five
years.
Generally speaking, intensive search for the primary does not improve survival.
Primary sites
Primary sites / Number
- Lung 23
- Ovary* 11
- Breast* 10
- Colon 8
- Gastric 6
- Kidney 6
- Prostate* 5
- Pancreas 4
- Melanoma 3
- Adrenal 2
- Thyroid* 2
- Germ cell* 2
- Hepatoma 2
- Lymphoma* 2
- Mesothelioma 1
- Nasopharyngeal 1
- Total 88
* Treatable primary site.
From Kirsten, Chung, Leary, Ng, Hedley & Tattersall, 1987
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Prognostic Factors:
- Good performance status
- Absence of excessive weight loss
- Age under 35
- Presentation with lymphadenopathy especially high cervical and axillary,
tend to have a prolonged survival
- Number of sites involved - a higher number being associated with a
worse prognosis.
Management:
About 10% of patients with CUP had treatable tumour types. Investigations
are therefore aimed at identifying the treatable tumours.
Treatable tumours which may present as cancer of unknown primary site:
Cure possible
- Germ cell tumours
- Hodgkin's disease
- Non-Hodgkin's lymphoma
- Thyroid cancer
- Trophoblastic tumours
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Effective Palliation
Chemoresponsive (>50%):
- Breast cancer
- Gastric cancer
- Head and neck cancer
- Ovarian cancer
- Sarcomas
- Small cell lung cancer
Hormonal treatment:
- Breast cancer
- Endometrial cancer
- Prostatic cancer
- Thyroid cancer
From Lindeman GJ, Tattersall MHN. Tumours of Unknown Primary Site. Oxford Textbook of Oncology.Ed. Peekham MJ, Pinedo B, Vevareni V. (In prep).
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Professor Martin Tattersall, Ludwig Institute for Cancer Research, University of Sydney, NSW, Australia
References:
1. Kirsten F, Chung HC, Leary JA, Ng AB, Hedley DW, Tattersall
MHN. Metastatic Adeno or Undifferentiated Carcinoma from an Unknown Primary
Site - Natural History and Guidelines for Identification of Treatable Subsets.
Quarterly Journal of Medicine, New Series 62, No. 238, pp. 143-161,
February, 1987.
2. Lindeman GJ, Tattersall MHN. Tumours of Unknown Primary
Site. Oxford Textbook of Oncology. Ed. Peekham MJ, Pinedo B, Vevareni
V. (In prep).
3. Holmes FF, Fouts TL (1970) Metastatic Cancer of Unknown
Primary Site. Cancer 26:1431-5.
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