There was a steady increase in the number of patients who received HDT for lymphoma from 1987 until a maximum was reached in 2004. In the last few years the figure has remained relatively stable, or perhaps shown a slight decrease. This may be attributed in part to the fact that primary treatment for several lymphoma types has substantially improved in the past 10 – 15 years, which is reflected in the Cancer Registry of Norway’s survival figures for lymphoma (5). The main reason for this is most likely the introduction of rituximab (anti-CD20 antibody), which has resulted in fewer and later relapses of all types of B-cell lymphomas (6). The primary treatment of Burkitt’s lymphoma over these 25 years has improved greatly, so that these patients now seldom need HDT (7). In addition, most of the indications related to lymphoma have been tested over time. In some clinical situations no benefit has been shown for HDT compared to less toxic cancer treatment (1). In refining the treatment, emphasis is now being placed on improved induction therapy to increase the remission rates before the HDT, in order for more people to undergo this treatment and hopefully reduce later relapse (1).
In the first few years the patient selection was stringent, and only young and otherwise healthy patients were considered for HDT. With increasing experience, improved supportive therapy, and last but not least, progress such as stem-cell harvesting from blood rather than bone marrow, it has been possible to achieve reduced treatment-related morbidity and mortality, as well as lower costs (8). The therapy is thereby also relevant for older patients with more comorbidity, and HDT is currently offered to more elderly patients than in the first few years, as illustrated by the figures for the two periods – those treated in the period 1987 – 95 were 11 years younger (median) than those treated in the period 1996 – 2008.
Overall the Radium Hospital of Norway has performed HDT on the greatest number of lymphoma patients. It was the only treating hospital in the period 1987 – 95 and had 60 % of all HDT patients following the regionalisation in 1996.
For Norway as a whole, the number of HDT therapies for lymphoma has been 0.73 per 100 000, which is comparable to the treatment activity in Western Europe and the rest of Scandinavia (9). When adjusted for the population base, the highest number of lymphoma patients who have received HDT are resident in the Northern Norway Health Region, followed by the South-Eastern Norway Health Region, the Western Norway Health Region and the Central Norway Health Region. Our data do not explain what these differences can be attributed to. One reason may be that it is a matter of discussion whether and when in the course of the disease HDT should be offered for particular lymphoma types, for example transformed lymphomas and follicular lymphomas, in relation to other treatment options. This gives more scope for clinical discretion and local tradition. In addition, participation in international studies may be a contributory factor.
Early mortality varied from 1 % for Hodgkin’s lymphoma to 9 % for aggressive/very aggressive lymphomas. This corresponds to previously published studies, in which treatment-related mortality of 1 – 10 % for Hodgkin’s lymphoma (8, 10, 11) and 4 – 10 % for non-Hodgkin’s lymphoma (8, 12, 13) was reported. Since we do not have complete details on causes of death for the whole population, in this study we have defined early mortality as death within 100 days following HDT, irrespective of cause of death. This will therefore also include early lymphoma-related mortality in addition to direct, treatment-related mortality.
We found a five-year overall survival rate of 64 % following HDT for all lymphomas combined. In an American single-centre study published in 2012, five-year survival for Hodgkin’s lymphoma and non-Hodgkin’s lymphoma of 59 % and 62 %, respectively, was found (14). In other studies of specific lymphoma types, three-year survival varies between 55 % and 80 % (11) – (13, 15, 16). More than half of the lymphoma patients are alive ten years after the HDT. Most of the patients had relapsed lymphoma or a disease that was resistant to conventional treatment, so that the prognosis was poor without HDT. In our opinion, it has been a life-saving treatment for most of these patients.
Altogether 411 lymphoma patients were alive following HDT at the start of 2011, and these represent a group of cancer survivors who have undergone very intensive treatment. A significant proportion of these have also had several rounds of chemotherapy and/or radiotherapy before receiving HDT. According to national guidelines, these patients should be followed up with regular controls (17). We know from earlier studies, both Norwegian and international, that certain groups of lymphoma patients have an elevated risk of developing late effects after treatment, such as hormonal dysfunctions, cardiovascular diseases, second cancers and chronic fatigue (18) – (21). The prevalence of and risk factors for late effects have not been specifically investigated in lymphoma patients who have received HDT. This is now being investigated in a national follow-up study in which all the 411 patients who are alive following HDT are also being offered a comprehensive medical control.