Back Pain : When Cancer is Bone Deep
Many people would have experienced back pain at some point in our life, and it is a common reason for work-related absence or a visit to the doctor’s. Although back pain may be painful and uncomfortable, it is not usually serious, but in some instances, it may portend a more ominous cause.
When does a back pain signify a real threat to your health? One should seek medical attention early if the pain becomes constant or progressively severe with no significant relief at rest, or if it interrupts your sleep. It becomes even more pertinent if it is accompanied by neurological deficits such as weakness and numbness in the legs or other symptoms, such as unexplained weight loss, and loss of bladder and bowel control.
Table 1. Causes of back pain
Causes of Back Pain
Injury to muscles & ligaments
Degenerative joint disease – osteoarthritis, spondylosis, spinal stenosis
Inflammatory – ankylosing spondylitis
Infection – tuberculosis
Osteoporosis – compression fracture
Cancer – mestastasis to spine, multiple myeloma
My Patient – Mr G
I recall one such patient with severe back pain whom I was asked to see in the middle of the night several years ago. The young man lay sprawled across the hospital bed when I entered the room. One side of his face twitched, pulling his expression into a lopsided frown and then into a grimace of pain. Mr G, a 35-year-old, had been healthy until a few months earlier, when he first noticed a throbbing lower back pain. He initially attributed the back pain to his regular tennis sessions and did not pay much attention to it. As the weeks went by, Mr G started noticing the back pain becoming more severe and frequent. He consulted his family physician who told him it was likely related to “muscle” injury from his regular tennis games and prescribed him with painkillers. Although the painkillers did provide temporary respite, he continued to have persistent symptoms over the course of the next few weeks. In that period of time, he had seen three other doctors who prescribed him with stronger painkillers and he even consulted a chiropractor, but to no avail.
Mr G was eventually referred to an orthopedic specialist, as the pain became more severe and was also experiencing numbness in both legs. He was immediately sent to have a magnetic resonance imaging (MRI) of the lumbar spine. Soon afterward, he received a call from his doctor and asked to see him right away. The MRI scans had revealed multiple bony lesions and a fracture seen in one of the vertebral body which was compressing on his spinal cord. His doctor explained to him that he had to be admitted to hospital and would require surgery to alleviate the compression on his spinal cord. It was that same night, that I was called in to see him prior to his surgery. Thankfully, his surgery went smoothly with no complications. The histology result from his surgery confirmed that he had multiple myeloma.
What is Multiple Myeloma?
Multiple myeloma is a cancer that arises from plasma cells, a type of white blood cell that is produced in the bone marrow. The main function of normal plasma cells is to produce antibodies, also called immunoglobulins, to help fight against infections. However, in myeloma, these abnormal plasma cells produces non-functioning antibodies, called paraproteins, which builds up over time in the blood and urine. It is the measurement of these paraproteins that myeloma is diagnosed and monitored. It is not clear what causes myeloma. But there are some known risk factors associated with multiple myeloma such as elderly age, male gender, black ethnicity and a history of monoclonal gammopathy of undetermined significance (MGUS).
As the cell of origin for myeloma are from the aberrant plasma cells in the bone marrow, it can therefore affect any bones in the body. The symptoms of multiple myeloma can be divided into those associated with disease in the affected bone and bone marrow, eg. bone pain, vertebral fractures, anemia, elevated calcium levels and in severe case, compression on the spinal cord, as seen in my patient. The other group of symptoms are related to the accumulation of the paraproteins in the blood and urine, leading to kidney damage and increased risk of infections.
How is Multiple Myeloma Diagnosed?
FA standard work-up for myeloma will include performing laboratory tests such as measurement of the paraproteins in the blood and urine, using protein electrophoresis and immunofixation techniques. Bone marrow biopsy is a crucial part of the work-up, both for diagnostic purpose and also to characterize the various genetic subtypes. With a better understanding of the biology of myeloma, it is now known it is not one entity but a heterogenous disease. There are different genetic subtypes of myeloma , with each subtype having a slightly different clinical course and survival outcome. A full body PET/CT scan or a skeletal bone survey using regular Xray imaging is also done prior to treatment. This is useful in determining the extent of bone involvement by the myeloma
Table 2. Initial Diagnostic Work-up for Multiple Myeloma
Full blood count
Creatinine, electrolytes, calcium, albumin
Serum & urine protein electrophoresis (SPEP & UPEP)
Serum & urine immunofixation electrophoresis
Serum & urine free light chain assay
Bone Marrow Biopsy
PET/CT scan or Skeletal survey
MRI for suspected vertebral compression
Coming back to Mr G, he underwent all the appropriate investigations and was soon started on chemotherapy within a week of surgery. There have been significant advances made in the treatment of myeloma. The chemotherapy used to treat myeloma today are the newer type, called targeted chemotherapy. They are more effective in treating myeloma compared to the older drugs used and are generally associated with less side effects. Mr G, had a very good response to his treatment and is currently in complete remission, which means he has no evidence of myeloma in his body.
Multiple myeloma is one of the many successes in cancer treatment in the modern era, many more myeloma patients are surviving longer. It is indeed encouraging to see how far we have come in the treatment of myeloma, once thought to be a dreaded disease with poor outcomes. I personally would never have envisage that from the time I started my career as a doctor in the nineties, that multiple myeloma would one day be treated like a chronic illness. Sure, we still have some ways to go in finding a cure for myeloma, but I would say, we are definitely headed in the right direction. Seeing my patients alive and leading fulfilling lives of their own is my greatest reward as their doctor!
Dr Kevin Tay
ABIM Int. Med (USA)
ABIM Med Onc(USA)
FAMS (Medical Oncology)