Spinal metastasis of bronchopulmonary cancer: Interest of a Spine surgery and prognostic scales value


 Backgroundlung cancer is the first mortality cause by cancer around the world. Bones metastasis occurrence is a common eventuality in case of lung cancer (40% at the diagnosis). In order to evaluate the indications and measure the effectiveness of surgery in the management of PBC spinal metastases, we report a series of 52 patients.MethodsDuring 6 years, from January 2009 to December 2014 at the Neurosurgery Unit of Marseille North Hospital (France), we studied retrospectively 52 patients records, who underwent a surgery for spinal metastasis of lung cancer. The study was only about patients which metastases were surgically treated. We used Stata software for the computation, and concerning the linear regression, all values under 0.1 were considered significant.Resultsthe average age was 63.6 years (39–80 years) with a sex ratio of 3. Non-small cell lung cancer was the most common, ie 36 cases (69.2%). Rachialgia associated to vertebral fracture with medullar compression was the most common clinical presentation (31 cases or 59.6%). SINS score (spinal instability neoplastic score) was equal or above 7 in 41 cases (78.9%). The general condition (Karnofski) was medium in 35 cases (67.4%). Survival prediction beyond 12 months was null according to Tokuhashi Index. The surgical indication was essentially palliative. Evolution was characterised by painful symptomatology regression in 44 cases (84.6%), stabilization of initially unstable lesion and motor deficit improvement in 48.3 % of cases. The average survival time following the surgery was 16 months.ConclusionOur results show the interest of surgery for pain relief and spinal stabilization in patient with spinal metastasis of lung cancer, and the relativity of predictive survival score.


Introduction
Bronchopulmonary cancer (PBC) is one of the most common cancers in men, and the rst mortality cause by cancer around the world [1,5]. Almost half of non-small cell bronchopulmonary cancers and 2/3 of small cell cancers are from the outset metastatic at the diagnosis [4,26]. Bones metastasis is a common eventuality in case of bronchopulmonary cancer. Almost 40% of patients present bones metastasis at the diagnosis or during the lung cancer evolution, and 40% of them are spinal metastases [21]. Spinal metastasis commonly occurs in dorsal spine (20%) or lumbar spine (15%). Cervical locations are more unusual (5%) [19]. The evolution of the spinal lesions was characterized in 50% of cases by osseous events as pain, fracture, hypercalcemia of malignancy and/ or medullar compression. Medullar compression is the most signi cant event, threatening the functional prognosis [2]. Those elements encourage to an early and optimal care of the vertebral bones lesions in order to prevent the medullar compression [15].
In this work, we report a series of 52 patients operated on for spinal metastases of PBC with the aim of evaluating the indications and measuring the effectiveness of spinal surgery in the management of these lesions.

Materials And Methods
We realized a retrospective study in a period of 6 years with 52 patients records. In 36.5% of cases, it was 1 or 2 metastasis and in 63.5% cases more than 2 metastasis. Metastasis was synchronous in 82.7% of cases and metachronous in 17.3% of cases.
All patients had rachialgia, which was isolated in 6 cases (11.5%), associated in 15 cases (28.9%) with a vertebral fracture without nerve compression and in 31 cases with spinal cord compression (59.6%) with complete de cit (Frankel A-B) in 11 patients and incomplete de cit (Frankel C-D) in 20 patients. The average VAS was 6.9 with extremes ranging from 6 to 10. This pain was moderate in 30 cases (57.6%) and severe in 22 cases (42.4%).
The SINS score (spinal instability neoplasic score) was equal to or above 7 in 41 cases (78.9%) and under 7 in 11 cases (21.1%).  Table 2 and Tomita scale in Table 3.  Group B (4-5) Group C (6-7) Group D (8-10) of isolated fever. Post-surgery survival was less than 6 months for 36 patients, 6-12 months for 8 patients, and more than 12 months for 8 patients. Survival as a function of the Tokuhashi score is summarized in Fig. 1 and the parameters that in uenced it are summarized in Table 4.

Discussion
Spinal metastases are frequently observed complications in the malignant disease at terminal stage [20].
At least 30 to 90% of patients who died of cancer had spinal metastasis in cadaveric studies [3,8,38]. The average age of our series was 63.6 years. Indeed, spinal metastasis has a high incidence in people aged 40 to 65 years, that match with the period where the risk of cancer is at the highest [25]. Men are most susceptible to develop spinal metastasis, thus probably re ecting the men's slight higher prevalence of developing spinal metastasis of lung cancer and of prostate cancer against symptomatic breast cancer [25]. This man predominance is considerably observed in our series (39 men/13 women).
The NSCLC of adenocarcinoma type was the most common in our series (69.2%). Histological type varies according to the studies. Sun & Al [32], in 2011, reported an incidence of 23% of osseous metastasis in a retrospective series of 1166 NSCLC.
Predominance of dorsal localization (30 %) is also reported by Patricia & Al in their series (49 %) [24]. In 36.5% of cases, it was 1 or 2 metastasis and in 63.5% of cases, more than 2 metastases. Metastasis was synchronous in 82.7% of cases and metachronous in 17.3 % of cases. Sioutos and Col [31] noticed that ambulatory patients in preoperative, and whose metastasis only concerned one vertebra, had statistically survived more than non-ambulatory patients whose metastasis concerned several vertebral levels.
Depending on the extent and the localization, they cause variable symptoms from pain to neurological de cit (complete or partial) [19]. Those osseous spinal metastases occur most often at the posterior part of vertebral body [20]. When they extend to the epidural space and are compressing the spinal cord, they are presented as a medullar compression of neoplastic origin [7]. In our series, pain was the main symptom associated in 59.6% to a medullar compression presentation. The preoperative SINS (spinal instability neoplastic score) was evaluated in all patients as previously described [11]. A score under 7 means stability, between 7 and 12 corresponds to an indeterminate or upcoming instability and a score from 13 to 18 suggests instability. This score can be used as a guide for making the surgical decision, because unstable lesions are most susceptible to require stabilization for a long-term management of metastatic diseases of the vertebral column [24].
Extra spinal metastasis was present in 57.6 % of cases in our series. Tumorous extension was evaluated by TNM classi cation, the stage 4 was the most common with 88.6% of cases. Functional consequences were appreciated by Karnofsky Index, which has an important part in our decision making. In our series, it was good in 28 % of cases (80-100), moderate in 67.4% (50-70) and poor in 3.8% (10-40%). It was equal or above 70% in 33 patients and under 70% in 9 patients for Patricia and Al's series [24].
Survival was evaluated by Tokuhashi Index, some authors covered the topics of survival after a surgery for spinal metastasis [35,36]. Indeed, Tokuhashi and Col [34] have studied the results of 64 patients who underwent surgery for spinal metastasis. They included all primary diagnosis and surgery performed for diverse indications including pain and paralysis. Based on this, they formulate speci c parameters including general condition, number of osseous extra spinal metastasis, vertebral metastasis number, presence of lesions in other internal organs, primary lesion localization, spinal cord lesion severity.
A score of 9 or above was predictive of at least 12 months of survival, a score of 8 or weaker indicate survival of less than 12 months and a score of 5 and under predicted 3 month or less of survival. Based on those data, it appears that the Tokuhashi system can be a precious tool in preoperative discussions and the decision making; its values were con rmed by other authors. Enkaoua, & al. [9] found it predictive of survival after surgery for most of patients presenting spinal metastasis. Although Tomita's scale [35] should not be overlooked, it still can be used to predict survival (Table 4). In our series, 48 patients had survival prediction of less than 6 months (Tokuhashi 0-8) and 4 patients a prediction of 6 to 12 months (9)(10)(11). There was no patient with a survival prediction above 12 months; as a matter of fact, the nature of the vertebral ailment which is secondary to a lung cancer is a bad prognosis element [13,34,35]. Thus, the Van der Linden team [36] found a median survival of 2.9 months for the patients suffering from spinal metastasis of lung cancer unlike our series where we found a median survival of 16 months. In our series, Tokuhashi's group C (12-15) and Tomita's group A (2-3), which correspond to good prognosis groups, were not found because of the high severity and mortality of bronchopulmonary cancers at the time of diagnosis. This partly proves the inadequacy and relativity of the classic prognosis scores (Tokuhashi and Tomita) in PBCs. The non-representation of good prognosis groups in PBC should lead us to set up a speci c prognostic classi cation of PBC spinal metastases considering all groups of patients.
Surgery was essentially palliative in our series; the main objective was to relieve pain and restore the stability. The palliative surgery allowed pain control, vertebral column stabilization, dural sheath release in case of medullar or root compression [2]. There is a lot of technics and surgical approaches which can be chosen depending on the area to treat, the medullar compression severity, the risk of instability and the patient general condition [2]. Vertebroplasty is indicated for spinal mechanical pain before or after surgery and provides a rapid relief in less than 12 hours [22]. The other consolidation technics are kyphoplasty (Fig. 2) and stentoplasty or percutaneous osteosynthesis when we doubt of the su ciency of cementoplasty alone or with stent to stabilize the spine [2]. Other surgical options are corpectomy associated to a reconstruction by vertebral prosthesis (Fig. 3), laminectomy and stabilization by osteosynthesis (Fig. 4) and vertebrectomy [10,18]. The surgical treatment has allowed the regression of the painful symptomatology in 84.6% of patients of our series, and allowed to stabilize the spine for all patients.
The after-surgery pain relief rate for metastatic tumors was generally high. Weigel [12,29]. The median survival of patients with advanced lung cancer improved from 6 to 12 months with introduction of new treatment diagram combined with monoclonal antibodies, which proceed as angiogenesis inhibitor [28,29]. Immunotherapy, which e ciency in improving the survival of bone metastases was rst demonstrated by the retrospective analysis of Tamiya et al [33].

Conclusion
Our results show evidence of the interest of surgery in pain relief and spine stabilization for patients carrying spine metastasis of lung cancer. Survival predictive scores for patients with spinal metastases (Tokuhashi, Tomita) are of limited applicability to PBC cancer metastasis due to the lack of good prognosis groups. Nevertheless, given the high morbidity and mortality of bronchopulmonary cancers, it would be necessary to implement a speci c classi cation for PBC spinal metastases centered on the patient (personalized medicine) for a better assessment of the survival prediction for these patients.

Declarations
Ethical approval Approval was obtained from the ethics committee of the Marseille North Hospital in France. The procedures used in this study adhere to the tenets of the Declaration of Helsinki. For this type of study formal consent is not required.
This article does not contain any studies with human participants or animals performed by any of the authors.