Spinal metastasis cases almost triple over two decades in Ireland

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A nationwide analysis of metastatic bone disease—believed by the authors to be the first of its kind in the world—has found that cases of spinal metastasis have increased by 182% from 1994 to 2012. The study used the National Cancer Registry of Ireland to evaluate data from 14,495 cases of metastatic bone disease to track the increase in prevalence year-on-year, as well as predict the clinical and financial burden facing Ireland in the future. The study was presented at Eurospine (Berlin, Germany; 5–7 October 2016) by lead author, Fergus J McCabe, of the National University of Ireland, Galway, Ireland.

According to the study authors, whilst bone is the “third most common site of metastatic cancer”, there is a paucity of research on its “epidemiology, molecular basis and management.” Speculating that the number of cases of the disease had risen significantly over the past two decades, the team aimed to map the epidemiology and aetiology of bone disease in Ireland, and predict the consequences facing orthopaedic surgery in the country.

Among other data, the National Cancer Registry of Ireland contains demographic, mortality and one-year treatment information for all diagnosed cancer cases in the Republic of Ireland. The research team included “all cases of metastatic bone disease in the Republic of Ireland diagnosed within one year of the primary diagnosis.”

Of the 14,495 cases of metastatic bone disease, 53% of those with location recorded (n=7,930) occurred in the spine (n=4,227). This was the most concentrated site amongst all cases, and was the most frequent site of first bone metastasis (n=3,740, 47%).

The number of diagnosed bone metastasis cases rose almost every year from 1994 (n=494) to 2012 (n=995), peaking in 2011 (1072). This was an increase of 108% over the 19 years, with a 63% increase in crude incidence rates, and a 51% increase when standardised for age. The researchers adjusted their data in line with age and gender statistics from the Irish Central Statistics Office and the 1976 European Standard Population. They found that 64% of this increase could be attributed to non-demographic factors.

When looking specifically at spinal metastasis, the researchers found more dramatic increases, again almost year-on-year. In 1994 there were 124 diagnosed cases in Ireland, rising to 350 in 2012. Again, 2011 saw a peak in spinal metastasis cases, with 354. From 1994 to 2012, the researchers discovered a 182% rise in cases, with a 122% increase in crude incidence and a 107% rise in age-standardised incidence. Adjusting for demographic factors, 80% of this increase was attributed to non-demographic factors.

Significant increases were seen in annual per cent change in incidence over the two decades across the registry for both total bone metastasis cases (p<0.05) and spine-only metastasis cases (p<0.05), for both genders (p<0.05), and for all age groups (≤44 years, 45-64 years and ≥65 years, p<0.05).

Speculating as to why Ireland had appeared to experience such a dramatic increase in spinal metastasis cases, McCabe suggested that earlier detection, improved case recording and a rise in the true incidence of bone metastasis could offer part of the explanation.

The team further evaluated the registry data to discover the primary cancers most commonly followed by bone and spinal metastasis. Lung was the most common primary site of cancer associated with both conditions, occurring in 30% of bone and 33% of spinal metastasis cases. Prostate cancer was the second most commonly-associated primary cancer (bone, 26%; spine, 20%).  A marked proportional increase was reported in lung as a primary site from 1999 onwards in the case of overall bone metastasis, and from 2002 in the case of spinal metastasis.

Researchers used their results to try and map the growing clinical and financial burden of the increase in spinal metastatic disease cases in Ireland. According to the UK’s National Institute for Health and Care Excellence, McCabe said, “All symptomatic spinal metastasis cases should be reviewed by a spinal surgeon.” Given the stark increase in cases, this represents a growing clinical burden which does not appear to be slowing. The authors noted that three specialist spinal centres are expected to be available over the coming years in the country (Dublin, Cork and Galway). With upwards of 350 cases expected to be diagnosed each year going forward, this makes for at least 117 cases per unit, per year.

Given the availability of new techniques, such as percutaneous pedicle screw instrumentation, radiofrequency tumour ablation, kyphoplasty with brachytherapy, and the rise in minimally invasive spinal surgery, McCabe suggested that “previously unfit patients will undergo surgical intervention.” This increased clinical burden translates into a significant financial cost. Estimating a cost of between €36,616 and €87,814 per spinal referral, the team guessed a total financial burden in 2012 of between €12,815,600 and €30,734,900 for the 350 spinal metastasis cases. This works out at between €4,271,866 and €10,244,967 per spinal centre.

Concluding, McCabe highlighted that the increase in spinal metastasis cases found by the researchers was “greater than one would expect with demographic changes alone.” Commenting on the increased financial burden, McCabe said that the dramatic trend had “significant infrastructural and cost implications for the Irish health service.”