The medical records at the Institute of Nuclear Medicine & Allied Sciences (INMAS), Dhaka, were reviewed retrospectively to identify all patients attended January July 2015 with a lung cancer. Lung cancer in all patients was confirmed histopathologically, and patients underwent whole-body scintigraphy for evaluation of skeletal metastases.
Reviewed were retrospectively all patient's records and imaging reports. Patient with clinical and laboratory evidence of infection, trauma, metabolic disease or arthropathy were not included in the study. A total of 47 patients met the inclusion criteria. Bone scan (BS) was performed by the intravenous administration of technetium 99m methylene diphosphonate (MDP) at a dose of 20 mCi. Images were obtained on a dual head gamma camera (Siemens Health Care System). Bone phase images were taken approximately three hrs after injection of the radiotracer and the scan time is about 15 minutes for a whole body scan.
Two experienced nuclear medicine physicians interpreted the bone scans as positive for bone metastasis if they contained one or more abnormal focal increased uptake sites.
Bone scan findings were compared with other imaging modalities, such as simple radiography (local X-ray), Computed Tomography (CT), Magnetic Resonance Imaging (MRI) or with histopathology findings (Image guided biopsy).
Result:
The mean age of the patients was Mean ± SD was 55.5 ± 12.5 with range from 31 to 90 years.
Of the total 47 patients, 38, (80%) were male and nine (20%) were female. Out of 47 cases 36 (77%) were diagnosed as positive for skeletal metastasis by bone scan and 11 (23%) were negative for bony metastasis.
Table I shows the distribution of study patients by skeletal metastases. Maximum 36 (77%) cases had skeletal metastases.
Skeletal metastases |
Frequency |
Percentage |
Positive |
36 |
77 |
Negative |
11 |
23 |
Total |
47 |
100.0 |
Among the 36 patients, maximum were non small cell lung cancer (NSCLC), 28 patients (78%) were histopathologically diagnosed as adenocarcinoma, seven (19%) patients had squamous cell carcinoma and only one patient (3%) had small cell carcinoma. (fig 1)
Fig 1: Pie chart showing distribution of the bone scan positive patients, according to histopathological types: (n= 36)
Of the 36 patients, 28 (78%) had multiple infiltrative lesions in bone scan and eight (22%) had solitary lesion and 20 (56%) had characteristic bone pain, but 16 patients (44%) were asymptomatic.
Table II: shows the distribution of bone scan positive patients by characteristic bone pain was Maximum in 20 (56%) cases had characteristic bone pain.
Bone pain |
Frequency |
Percentage |
Positive |
20 |
56 |
Negative |
16 |
44 |
Total |
36 |
100.0 |
Twenty tow patients (61%) received both chemotherapy (CT) and radiotherapy (RT), three patients (8%) were underwent surgery and received chemotherapy also. 11 patients (31%) were newly diagnosed, and had no treatment history. (Fig 2)
Figure 2: Distribution of the bone scan positive patients , according to treatment status: (n= 36)
Serum alkaline phosphatase was elevated in 16 patients, among 36 positive patients. In present study, the distribution of lesions in bone scan had recorded.
Maximum lesions were found on axial skeleton. 47 % lesions were found in ribs, 27% lesions were in lumbar vertebrae, 20% lesions were found in thoracic vertebrae, 20% found in joints, 16% found in long bones (femur and humerus), 11% in skull bones, 22% in pelvic bones, 5% in clavicle and 3% lesions were found in scapula. (Fig 3).
Figure 3: Distribution of the metastatic lesions according to anatomic locations
Bone scan findings were compared with other imaging modalities, such as simple radiography (local X-ray), Computed Tomography (CT), Magnetic Resonance Imaging (MRI) or with histopathology findings (Image guided biopsy). Out of 36 patients, 20 has CT guided biopsy reports and all 20 patients were diagnosed as positive for bone metastasis in pathological test also.
Figure-4
•50 yrs male, diagnosed case of adenocarcinoma right lung, no history of surgery and radiotherapy, chemotherapy was ongoing ,2 cycles were given.
•
Bone scintiscan findings: Multiple infiltrative lesions on both frontal and left parietal region, upper shaft of left humerus ,manubrium sterni including left sternoclavicular joint, left 2
nd, 6
th, right 7
th rib anteriorly, right 3
rd rib posteriorly, L3 vertebra, both pubic bones, both acetabulum ,trochantaric region of right femur.
•Bone scan findings compared with local X- ray findings and findings were compatible. CT guided needle biopsy done from L3 vertebral body showed metastatic adenocarcinoma
Discussion
Lung cancer is the most common neoplasm worldwide and the bone is one of the most common metastatic sites for lung cancer.
5,6
Non-small-cell lung cancer (NSCLC) accounts for 80-85% of all lung cancer diagnoses, the majority of which present as late-stage disease, primarily owing to the asymptomatic nature of early disease and commonly metastasize to bone. In this study, maximum 28 patients (78%) with positive scintigraphy report were histopathol-ogically diagnosed as adenocarcinoma, study showed that adenocarcinoma was the most common cell type found in patients with bone metastases, in their study.
7
In the present study, high incidence of bone metastasis from lung cancer was seen in the axial skeleton like vertebra, rib, and pelvis. The distribution of the lesions are similar to the previous studies.
8 In bone metastasis from lung cancer, metastasis may occur easily at an axial bone through the vertebral vein system at an early stage and then at an appendicular bone in more advanced stages of the disease. The prognosis is poorer in patients with metastasis to the appendicular bone.
8
Ebert et al have observed that bone metastasis was present in 20-30% of patients at the initial diagnosis of lung cancer in their study which strongly support the findings of present study.
9 In present study, out of 36 bone scan positive patients, 20 (56%) had characteristic bone pain, but 16 patients (44%) were asymptomatic. Serum alkaline phosphatase level was elevated in 16 among 36 positive patients. Iordanidou L et al found significant number of clinically asymptomatic patients diagnosed as positive for metastases on scintigraph.
10 Other studies reported that the prevalence of bone metastasis among patients who report bone pain was almost similar to patients who did not report bone pain.
Bone metastasis is a major determinant of treatment outcome, quality of life, and survival for lung cancer patients. The mean length of survival is substantially longer in patients with solitary-site metastasis than in patients with multiple-site metastases.
11
Joo-Won Min et al suggested in their study that in patients with disseminated disease who do not need evaluation of nodal staging, BS and the measurement of serum ALP concentration are sufficient for detecting asymptomatic metastatic bone lesions.
12 The author also reported that the sensitivity was 93.3%.
By different authors bone scan sensitivity was found about 62- 89%. 2 In our study 77% patients was found positive for metastases in whole body bone scintigraphy.
Conclusion: It may be recommended that Tc 99m MDP Bone scintiscanning should be used as the preferred screening investigation because of its low cost, wide availability, usefulness in imaging the entire skeleton and high sensitivity. It can plays a pivotal role for detection of skeletal metastasis, in ca lung patients in a developing country, like Bangladesh and can help the doctors in the rational approach of patient management in case of Ca Lung.
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