Risk of second primary malignancies following nasopharyngeal carcinoma in Hong Kong

Abstract

Nasopharyngeal carcinoma (NPC) is rare in most of the world but common among southeast Asians. Since NPC is usually diagnosed at relatively young ages and most patients now survive, the issue of second primary tumors (SPTs) has become important. Previous studies of SPTs among NPC survivors have given conflicting results. Data on patients with NPC diagnosed between 1996 and 2002 were abstracted from the medical records of two Hong Kong oncology centers. SPT incidence in these patients was compared to that of Hong Kong's general population using standardized incidence ratios (SIR). Eight-four patients were observed to have at least 1 SPT and 92 total additional cancers (SIR = 1.93, 95% CI = 1.55-2.37). The excess risk was greater for women and patients under 40 at diagnosis. Significant excesses were found for tongue, lung, nasal and middle ear, and brain cancers. The pattern of sites at which the greatest excess risk occurred is consistent with the hypothesis that much of the excess is due to treatment effects. The greater excess risk among patients diagnosed before 40 points to possible genetic influences. More research is needed to determine the reasons for greater excess risk among women.

Risk of second primary malignancy after nasopharyngeal carcinoma in the United States: A population‐based study

“…Given the male:female ratio of 2.48:1 in our study, the findings and demographics are fairly consistent with other studies . The results of second primary malignancies in this study agree somewhat with previous studies in Hong Kong, Taiwan, and pooled registries . However, there were more white patients and squamous cell carcinoma index of NPCs in our cohort, reflecting country variations and less Epstein–Barr virus‐related NPC.…”

“…In our cohort, however, we did not have a significant elevated risk of lymphoma/leukemia reported by the other studies, but as these other studies did not comment on baseline histological characteristics of their NPC cohorts, this may reflect that our cohort represented only those with a histology of squamous cell carcinoma or lymphoepithelial carcinoma, excluding those with other histological characteristics in NPC. Differing from the hospital‐based study from Taiwan, we did find a significantly increased risk of lung and bronchus carcinoma similar to the hospital‐based study in Hong Kong, the differences found may represent population, ethnic differences, or differences between hospital‐based and registry‐based studies. This could also represent etiological differences as more squamous cell carcinoma than undifferentiated carcinoma NPC was seen in our cohort and the effect of field cancerization of the aerodigestive tract.…”

“…The time period was chosen to include those patients who were diagnosed from the years 1973 to 2005 allowing for 5 years until the study end of 2010. Age group was classified into those <40 or ≥40 years old consistent with prior studies evaluating NPC . Year of diagnosis was separated into groups by decade.…”

“…Second primary malignancies are becoming increasingly important in patients being treated for carcinoma and increasingly recognized. This may be related to numerous factors, including genetic, environmental, treatment, and increased disease surveillance . In NPC, there have been studies demonstrating increased second primary malignancies in Hong Kong, Taiwan, Singapore, Canada, and Europe, although the patterns of second primary malignancies differ between countries.…”

Second primary squamous cell carcinoma in patients with nasopharyngeal carcinoma after radiotherapy‐Predictors and prognostic factors

“…However, some patients who develop second primary tumors may be treated at local community hospitals rather than present again or return to the regional cancer center. These may be the main factors for the lower rate of second primary tumors compared with other studies . The estimated rate may be lower than the actual incidence because a proportion of patients were lost to follow‐up or died before disease progression to the second primary tumor.…”