Clinical Investigation
Role of Definitive Radiation Therapy in Carcinoma of Unknown Primary in the Abdomen and Pelvis

https://doi.org/10.1016/j.ijrobp.2011.03.051Get rights and content

Objectives

Carcinoma of unknown primary (CUP) in the abdomen and pelvis is a heterogeneous group of cancers with no standard treatment. Considered by many to be incurable, these patients are often treated with chemotherapy alone. In this study, we determined the effectiveness of radiation therapy in combination with chemotherapy in patients with CUP in the abdomen and pelvis.

Patients and Methods

Medical records were reviewed for 37 patients with CUP treated with radiation therapy for disease located in the soft tissues and/or nodal basins of the abdomen and pelvis at the University of Texas M.D. Anderson Cancer between 2002 and 2009. All patients underwent chemotherapy, either before or concurrent with radiation therapy. Patients were selected for radiation therapy on the basis of histologic type, disease extent, and prior therapy response. Twenty patients underwent definitive radiation therapy (defined as radiation therapy targeting all known disease sites with at least 45 Gy) and 17 patients underwent palliative radiation therapy. Only 6 patients had surgical resection of their disease. Patient and treatment characteristics were extracted and the endpoints of local disease control, progression-free survival (PFS), overall survival (OS), and treatment-related toxicity incidence were analyzed.

Results

The 2-year PFS and OS rates for the entire cohort were 32% and 57%, respectively. However, in patients treated with definitive radiation therapy, the rates were 48% and 76%, and 7 patients lived more than 3 years after treatment with no evidence of disease progression. Nevertheless, radiation-associated toxicity was significant in this cohort, as 40% experienced Grade 2 or higher late toxicities.

Conclusions

The use of definitive radiation therapy should be considered in selected patients with CUP in the soft tissues or nodal basins of the abdomen and pelvis.

Introduction

Carcinoma of unknown primary (CUP) is a heterogeneous group of cancers in which regional or distant metastases are detected with no identifiable primary tumor (1). Because CUP represents metastatic disease, the initial treatment in most patients is chemotherapy (1). Unfortunately, in spite of significant improvements in tumor characterization 2, 3, staging 4, 5, and patient selection 6, 7, chemotherapy alone is not curative in most cases 8, 9, 10, 11, 12. However, in some patient subsets, the combination of chemotherapy and definitive local therapy can be curative 1, 13. These subsets include patients with metastases to the cervical 14, 15, 16, 17 or axillary lymph nodes 18, 19 and isolated metastases to the brain (20). These conditions are characterized by limited overall disease burden and a disease location that is amenable to definitive local therapy.

CUP in the soft tissue and lymph nodes of the abdomen and pelvis is generally considered be incurable. Some investigators have argued that aggressive local therapy is not indicated in these cases because, believing that metastases in these locations indicate widely disseminated disease (21). However, modern imaging (4) and pathologic evaluation 2, 3 techniques have allowed us to more accurately stage and characterize CUP (5). Further, modern conformal radiation therapy techniques have allowed us to deliver definitive radiation therapy to areas of the abdomen and pelvis while sparing surrounding normal tissues 22, 23, 24, 25, 26, 27. However, whether definitive local therapy for CUP in the abdomen and pelvis is beneficial is unknown. Therefore, the goal of this study was to determine whether radiation therapy was effective in CUP in the modern era, as measured by survival rates, local disease control, and toxicity.

Section snippets

Patients and Methods

After approval from our institution’s Internal Review Board, patients were identified through a search of the University of Texas M.D. Anderson Cancer Center Department of Radiation Oncology databases. In all, 381 patients with CUP were identified who were treated with radiation between 2002 and 2009. Of these, 40 patients were treated to metastatic sites in the soft tissues or nodal basins of the abdomen and/pelvis. Three of these patients had putative primary disease sites identified during

Cohort characteristics

The characteristics of the 37 patients in this study are shown in Table 1. Ten (27%) were men, and 27 (73%) were women, with a median age of 55 years (range, 37–74 years). In 21 patients (57%), disease was limited to the nodal basins of the abdomen and pelvis. Ten patients (27%) had disease in the nodal basins of the abdomen and pelvis and had evidence of metastasis outside the abdomen and pelvis. Six patients (16%) had disease in the soft tissues of the abdomen and pelvis (pelvic side wall [n

Discussion

CUP of the abdomen and pelvis is a heterogeneous group of tumors with no standard treatment approach and a poor overall prognosis. In this study, we found that definitive local therapy resulted in long-term disease control in patients with localized CUP involving the soft tissues and lymph node basins of the abdomen and pelvis.

The importance of locoregional disease control in CUP has been demonstrated in multiple disease sites 14, 15, 16, 17, 18, 19, 20. The best characterized sites of CUP

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      Similarly, in the series from MDACC, women treated with chemoradiation were alive with or without disease for an average of 22 months (range 6–48 months) (Table 2) (Clements et al., 2010). Larger series of a more diverse group of patients with unknown primaries of the abdomen and pelvis have also shown survival benefits using definitive radiotherapy (Kelly et al., 2012). In this series, each woman presented with hip pain and was found to have large volume disease in the pelvis and retroperitoneum.

    • Carcinoma of unknown primary in the inguinal lymph node region of squamous cell origin: A case series

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      Two courses of chemotherapy were given as induction chemotherapy that could reduce tumor bulk prior to concurrent chemoradiation and reduce the risk of distant metastasis. Kelly et al10 reported that locoregional radiation therapy is crucial for inguinal region CUP of squamous cell origin as CUP of the inguinal region generally behaves as locally advanced disease. All of our patients received a radical course of radiation therapy.

    Conflict of interest: none.

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