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Almost any time a physician treats a bony lesion or fracture pathological to the spine, the world of poor bone quality is entered. In order to improve understanding (and control) of the normal and diseased skeletal system, it is necessary to be conversant with a basic knowledge of these disorders affecting the spine. Therefore, basic laboratory tests, which can aid in the diagnostic work-up and evaluation of tumor recurrence, are reviewed in this chapter. It should be noted, though, that this chapter provides only an overview on the subject and it does not provide a complete review of all laboratory tests and prognostic factors applicable to spine tumor patients.

In the past, patients rarely questioned the therapeutic decisions made by their physicians. Physicians, in turn, were guided by the principle of “doing onto others as you would have done onto you” and were largely limited by their clinical experiences. Today, evidence-based medicine dictates most treatment decisions, and the role of the physician in educating patients about available therapeutic options is becoming increasingly critical. The patient’s autonomy has taken a more significant role in the ultimate treatment chosen.

Multiple myeloma (MM) is a clonal disorder of B-cell lymphocytic lineage characterized by malignant transformation of plasma cells. It accounts for approx 10% of all the hematological malignancies and 1% of all cancers in the United States. In the year 2000, MM was diagnosed in approx 13,700 people in the United States and accounted for 20% of deaths from hematological malignancies (). The median age of onset is 68 yr. It is slightly more frequent in women and the incidence in African-Americans is twice that of Whites. Both the overall incidence and specifically the incidence in African-Americans have been rising in recent years. A recent study explored whether dietary factors contribute to the risk of MM and the twofold higher incidence among Blacks compared with Whites in the United States. Data from a food frequency questionnaire were analyzed for 346 White and 193 Black subjects with MM, and 1086 White and 903 Black controls who participated in a population-based case-control study of MM in three areas of the United States. This study concluded that the greater use of vitamin C supplements by Whites and the higher frequency of obesity among Blacks may explain part of the higher incidence of MM among Blacks compared to Whites in the United States.

In the year 2002 there was an estimated 60,900 new cases of lymphoma in the United States, with 53,900 cases of non-Hodgkin’s lymphoma (NHL) and 7000 cases of Hodgkin’s lymphoma (). Estimated deaths in 2002 for NHL and Hodgkin’s lymphoma were 24,400 and 1400, respectively. The male to female ratio for both NHL and Hodgkin’s lymphoma is presently 1.1:1. Although the incidence of Hodgkin’s lymphoma has remained stable over the past several decades, there has been an increasing incidence of NHL in North America at a rate of approx 2 to 3% per year. NHL comprises 4% of male and female cancers in the United States, being the fifth most common malignancy among women (after breast, lung, colorectal, and uterine) and the sixth most common among men (after prostate, lung, colorectal, urinary bladder, and melanoma) ().

Carcinoma of the breast is the most frequent cancer in women in the United States and the second leading cause of cancer deaths. In the year 2005, it is estimated that more than 210,000 new cases will be diagnosed, while approx 40,000 will die from the disease. A slight decrease in mortality has been noted in recent years, attributable to improved screening practices as well as modest improvements in treatment ().

Among the major genitourinary neoplasms, prostate and renal cell carcinomas rank high among all epithelial neoplasms in the relative incidence of both bone metastases and spinal cord compression (,). Although advanced urothelial cancers (primarily bladder cancer) represent a relatively small number of patients, this neoplasm too has a relatively high predilection to spread to bone (). Although the fundamental management issues of skeletal metastases are similar within these neoplasms, the systemic therapies utilized to treat these diseases are very different; hormonal therapy for prostate cancer, immunotherapy for renal cell cancer, and systemic chemotherapy for advanced urothelial cancers. The relative effectiveness of these diverse therapies impact on some important aspects of the management of metastatic disease to the spine in patients with these neoplasms.

Among 965,000 new patients with cancer occurring yearly in the United States, bone metastases will eventually develop in 30 to 70% (). The most common site of metastases is the spine occurring in 50 to 70% of those with bone metastases (). In adults, malignant bone tumors arise most frequently from extraosseous epithelial primaries, whereas children usually have primaries from within bone (). Primaries most commonly associated with bone metastases are breast, prostate, lung, kidney, and thyroid carcinoma (,). Pain occurs in some, but not all, bone metastases as 33 to 50% of patients with skeletal metastases do not have pain (). The experience of pain is not particular to gender or primary tumor-related, nor is it predictable based on radiological appearance. The primary site of malignancy remains unidentified in 10% of patients with skeletal and spinal metastases. In most series of bone and spinal metastases, gastrointestinal primaries make up a similar percentage of those with unknown primaries (). The distribution of metastases within the spine follows the same pattern regardless of the primary site with few exceptions (). Spinal cord compression is the most feared complication of spinal metastases and the distribution of metastases within the spine does not correlate with the same risk of cord compression. The thoracic spine is most vulnerable.

In the United States, 172,570 new cases of lung cancer will be diagnosed in the year 2005 and 163,510 of these patients will die of the disease (). Lung cancer is currently the leading cause of cancer death in men and has now surpassed breast cancer in women (–). The median age at diagnosis is approx 60 yr. The highest incidence of lung cancer is noticed among Hawaiians and African-Americans in United States, and in Scotland and Wales, worldwide ().

Thyroid cancer, the most common endocrine malignancy, accounts for 1.1% of all the newly diagnosed malignancies in the United States (). It occurs three times more commonly in women. Its annual incidence has increased over the last few decades, possibly in part owing to improved diagnosis and cancer registration (). However, the mortality rates owing to thyroid cancer have decreased by 20% between the years 1973 and 1996, because of early diagnosis, and better surveillance and treatment.

The presence of metastatic cancer without evidence of its source is a common clinical entity representing between 3 and 15% of all cancer diagnoses. Patients with cancer of unknown primary (CUP) are heterogenous, having a wide variety of clinical presentations and pathological findings, resulting in diagnostic and treatment dilemmas for both the patient and clinician. Despite having a widely varying prognosis, with optimal treatment, some patients have the potential for long-term survival, whereas others are unlikely to respond to any type of treatment.