Carcinoma of Unknown Primary Origin - Characteristics, Diagnosis, and Treatment

Introduction

Carcinoma of unknown primary origin (CUP) is a diverse category of malignancies distinguished by the presence of metastatic disease in the absence of an identifiable original tumor at the time of presentation. Identifying patients with prognostically good illnesses is critical because they may benefit significantly from tailored therapy, including more prolonged survival. Therefore, a full search for the primary tumor is advised in carcinoma of unknown primary origin. It is uncertain whether carcinoma of an unknown primary source is a separate molecular genotype-phenotype compared to metastases from recognized malignancies. On the other hand, using a comprehensive immunohistochemistry panel and growing molecular data may construct a personalized therapy strategy for people with carcinoma of unknown primary origin, including the proper use of targeted drugs.

What Is Carcinoma of Unknown Primary Origin?

• Carcinoma of unknown primary origin is a varied category of malignancies distinguished by the development of metastatic disease in the absence of an identifiable original tumor at the time of initial presentation.

• Carcinoma of unknown primary origin has been found to account for two to five percent of all cancer cases.

• However, with imaging methods and targeted cancer treatments, the workup level in carcinoma of unknown primary origin should depend on clinical presentation, pathology, and the patient's capacity to tolerate therapy.

What Are the Biological Characteristics of Carcinoma of Unknown Primary Origin?

• The initial tumor in carcinoma of unknown primary origin may remain small and hence be difficult to identify clinically, or it may vanish after seeding the metastasis.

• It might be a malignant growth with more significant metastasis or survival compared to the underlying tumor.

• It is still unknown whether carcinoma of unknown primary origin metastasis is genetically and phenotypically distinct.

• Research has looked at the involvement of chromosomal and molecular abnormalities in carcinoma of unknown primary origin.

• However, no carcinoma of unknown primary source characteristics has been discovered that is distinct from metastasis from recognized original tumors.

• There are chromosomal 1 and 12 abnormalities and additional complicated abnormalities.

• Aneuploidy is also found in 70 percent of carcinoma of unknown primary origin patients with metastatic adenocarcinoma or undifferentiated cancer.

• Carcinoma of unknown primary origin has exhibited overexpression of various genes, including Ras, Bcl-2, Her-2, and p53.

How Is Carcinoma of Unknown Primary Origin Diagnosed?

The following tests diagnose the carcinoma of unknown primary origin:

• Past medical history - All of the previous history is recorded.

• Physical examination - Complete general examination of the body is done.

• Liver and kidney function tests - It is done to determine the accurate level of the enzymes of the liver and kidney.

• Blood tests - this includes hemoglobin and blood cell count tests.

• Chest radiography - To check the lining of the lung and the surrounding structures.

• Abdominal and pelvic analysis - To evaluate the organs present in the abdominal cavity.

• Mammography - This is the type of scan of the breast tissues.

• Prostate-specific antigen (PSA) test - PSA level is measured in the blood by a blood test.

How Is Carcinoma of Unknown Primary Origin Treated?

Various malignancies are involved, and the outcomes of carcinoma of unknown primary origin are challenging to understand. For most patients, systemic chemotherapy is the direct therapeutic technique; however, surgery, radiation therapy, and observation periods are helpful. Performance status, location and number of metastasis, response to treatment, and blood lactate dehydrogenase level are all prognostic variables.

What Is the Treatment for Women With Adenocarcinoma or Isolated Axillary Adenopathy?

• Suppose the mammography and sonography findings are negative. In that case, women with adenocarcinoma or isolated axillary adenopathy are treated for stage II or III breast cancer and are candidates for breast magnetic resonance imaging (MRI).

• If the breast magnetic resonance imaging results are favorable, lumpectomy and radiation treatment to the ipsilateral breast should be explored for local disease management.

• If the clinical and imaging findings imply breast cancer, the conventional treatment is axillary lymph node dissection followed by chemotherapy, radiation therapy, and, if necessary, hormone therapy.

• Patients with bulky nodal disease are frequently employed with neoadjuvant systemic treatment followed by surgery.

• The immunohistochemical study of estrogen and progesterone receptors, as well as Her-2/neu, can aid in determining the best therapy.

What Is the Treatment for Primary Peritoneal Carcinoma?

• Carcinoma of unknown primary origin with carcinomatosis and elevated CA-125 antigen features of ovarian cancer but no primary ovarian tumor discovered on transvaginal sonography or laparotomy is referred to as primary peritoneal papillary serous carcinoma (PPSC).

• Patients with primary peritoneal papillary serous carcinoma (PPSC) are eligible for ovarian cancer treatment, which includes cytoreductive surgery followed by adjuvant taxane- and platinum-based chemotherapy.

What Is the Treatment for Midline Adenopathy?

• Extragonadal germ cell malignancy is present in men with poorly differentiated or undifferentiated cancer presenting as midline adenopathy.

• Cytogenetic analysis for isochromosome 12p is used to identify extranodal germ cell malignancy, but it is now seldom employed.

• Patients with extragonadal germ cell carcinoma were often misdiagnosed with carcinoma of unknown primary origin in the past.

• Even without a definitive diagnosis of germ cell cancer, some individuals with poorly differentiated or undifferentiated carcinoma presenting as midline adenopathy responds to platinum-based combination treatment.

What Is the Treatment for Cervical Adenopathy in the Presence of Squamous Cell Carcinoma?

• Patients with cervical adenopathy and squamous cell carcinoma should have a triple endoscopy with samples taken from inconspicuous areas, a unilateral or bilateral tonsillectomy, and a scan of the neck and chest to look for the primary tumor and identify the tumor stage.

• People in the early stages of illness may benefit from node dissection and radiation treatment, which can result in long-term survival.

• Chemoradiation treatment or induction chemotherapy is often used and effective in bulky illnesses, although its efficacy in these patients is uncertain.

Conclusion

A full search for the main tumor is advised in carcinoma of unknown primary origin. Identifying individuals with prognostically good illnesses is critical because they may benefit significantly from tailored therapy and live longer. However, for the vast majority of carcinoma of unknown primary origin patients, resistance to conventional cytotoxic treatment develops repeatedly, and the prognosis is bleak. Response rates for recognized cancer types have increased progressively over the last decade; consequently, there is a prediction of great overall response rates with new tailored regimens for selected carcinoma of unknown primary origin patients. Thus, a personalized therapy regimen for carcinoma of unknown primary origin using a robust immunohistochemistry panel (directed approach) and developing molecular data is necessary.