METHODS
Medical reports of pediatric NPC patients (patients at or under the age of 19) treated between 1990 and
2017 and followed till the end 2020 were reviewed. SPMs are classified depending on the organ, histopathology,
location (whether in or out of the radiation field). Additionally time period between NPC
treatment and diagnosis of second primaries are recorded.
RESULTS
The median age of the 108 patients at diagnosis was 15 years (5-19 years). The male-to-female ratio was 2.1.
The median follow-up was 118 months (3-332 months). Eight patients developed 9 second malignancies
(one patient with two SPMs). Eight of SPMs were in the radiation field. SPMs developed at a median of
15 years (5-26 years) after the conclusion of the primary treatment. Among patients, whose malignancy
developed in the irradiation field 6 were treated primarily with complete surgical resection and 3 of them
died because of SPM.
CONCLUSION
Incidences of SPMs have been increasing in parallel with the increase in life expectancy of pediatric and
adolescent NPC survivors. Due to relatively high numbers of SPMs, pediatric/adult nasopharyngeal cancer
survivors should be followed regularly not only for recurrences and long term morbidities but also for second
malignancies which may be treated with curative surgeries and additional treatments when diagnosed
early. The patient follow-up should continue and patients should be evaluated comprehensively, taking
into account cancers outside the irradiation field. Since the most of the SPMs develops in the irradiation
field, prospective clinical studies investigating dose reduction in the treatment of pediatric NPC should be
considered and evaluated with further prospective trials.
Keywords: Adolescent; children; nasopharyngeal carcinoma; second primary malignancies
Pediatric/adolescent cancer survivors have an increased
risk of developing subsequent primary neoplasms,
which is estimated to be 10 times higher than
the general population and may occur due to the carcinogenic
influences of radiotherapy (RT), chemotherapeutic
agents, environmental carcinogens, and genetic
features.[
High-level clinical evidence for the management of
pediatric and adolescent patient populations is lacking.
Current patient evaluation and treatment protocols are
mostly derived from adult head-and-neck SCC protocols,
which rely on the adult patient population"s clinical
data.[
There are limited data on the incidence of SPMs
among pediatric and young NPC survivors.[
Treatment
The primary treatment was three courses of chemotherapy
followed by RT. Patients diagnosed during
1989-1991 were treated with cisplatin (80 mg/m2)-5-
fluorouracil (1000 mg/m2/d on days 1-4) combination,
during 1992-2007 with cisplatin (100 mg/m2/day),
epirubicin (90 mg/m2/day), and bleomycin (15 mg/m2/
day) combination and since 2008, cisplatin (100 mg/
m2/day) and epirubicin (90 mg/m2/day) combination
were administered with 3-week intervals. RT was administered
without concurrent chemotherapy.
All patients received external beam RT. Before 2011, conventional RT with two-dimensional treatment planning was used. The primary tumor and upper neck area were treated with two parallel opposed lateral fields, the lower cervical and supraclavicular regions were treated by a single anterior field using a median shield to protect the larynx and the spinal cord, with doses of 50 Gy by Co60 or 4-6 MV linear accelerator. The spinal cord was shielded after 46 Gy and the posterior lymphatic chains were treated with electron beams. A total median dose of 66 Gy (range 60-70 Gy) was administered in daily fractions of 1.8-2 Gy, 5 days a week for all the primary tumor and involved lymph nodes. Uninvolved cervical and supraclavicular regions received 45-50 Gy in daily fractions of 1.8-2 Gy, 5 days a week. Since 2011, intensity-modulated RT (IMRT) was used. The gross tumor volume (GTV) included the whole extent of disease in the primary nasopharyngeal lesion and cervical lymph nodes observed on magnetic resonance and/ or CT images. Accordingly, the clinical target volume (CTV) included all GTV with safety margins covering all potential subclinical disease sites; posterior nasal cavity, maxillary sinuses, clivus, basis cranii, inferior sphenoid sinus, pterygoid fossae, and retropharyngeal nodes with 0.5-1 cm margins. The main critical organs to be spared were the parotid glands, pituitary gland, cochlea, brain stem, spinal cord, larynx, eyes, lens, chiasma, optic nerves, and brachial plexus. Planning target volume was obtained by an additional 0.3-0.5 cm around CTVs.
Post-treatment imaging was performed by CT or MRI at 6-8 weeks and by PET-CT at 12 weeks after completion of the therapy. The periods for followup examinations were once in 3 months for the first 2 years after RT, every 4-6 months for the 3rd, 4th, and 5th years, and annually thereafter. During follow-up, imaging surveillance by CT or MRI was held every 6 months for the first 2 years and annually thereafter. PET-CT imaging was performed in case of clinical necessity. Histopathologic confirmation was obtained for diagnosis of second primary cancer. Locoregional MRI/CT and/or PET-CT were used for second primary cancer evaluation.
All patients were treated with cisplatin-based three courses of neoadjuvant chemotherapy by every 3 weeks interval followed by RT. Chemotherapy regimens used were cisplatin, 5-fluorouracil in 11 patients (90%) before 1992, cisplatin, epirubicin with or without bleomycin in 97 patients (90%) later-on. Eighty-one patients (75%) were treated with 2D-RT and 27 (25%) patients with IMRT. The median follow-up was 118 months (3-332 months).
In 15 (14%) patients, the disease continued and/or relapsed at a median of 8 months (range, 2-23 months). The failure sites were distant in 10 cases, distant and regional in three cases, distant and local one case, and distant and local and regional in one case.
During follow-up 21 patients died, 15 of them died due to progressive disease, three from the second malignancy, and the rest three deaths were unrelated to malignancy.
Second Malignancies
In eight patients, nine SPMs developed (a patient had
two SPMs). Excluding the SPM in the bladder, all were
in the irradiation field (Table
The site of SPM in our patients showed a significant risk of the oral cavity and pharyngeal cancers, which made up three of nine SPMs. Three of the nine SPMs were sarcomas (one osteosarcoma, one fibrosarcoma, and one high-grade sarcoma of the temporal fossa) and five of the nine SPMs were carcinomas. The patient with a SPM in his bladder was diagnosed with primitive neuroectodermal tumor (PNET), he received chemotherapy and RT, however, he died because of the progression of the second SPM. The other seven patients, whose second malignancies developed in the irradiation field, underwent curative surgeries; four are alive with no evidence of disease (NED) for a median of 7 years (3-15 years), one, who was with NED for 4 years, died from sepsis after reconstructive surgery of the mandible. Three of the patients died from progressive SPMs.
Among pediatric head-and-neck cancer patients,
the male gender was more prevalent in most studies,
accounting for approximately 60% of the primary
cases[
Adult female NPC survivors had a higher risk of
SPM than adult males in every interval[
The mean duration after the conclusion of the primary
treatment to the diagnosis of SPM was 5 years
for the younger patients (younger than age of 14) and
19 years for the older (14-18 years of age) patients.
Jouin et al.[
Population-based studies on adult patients have
shown that the SPM incidence was higher for patients
diagnosed before 40 years of age than later age.[
Radiation-induced tumors are the most serious late
complications in NPC survivors and the incidence rate
in adult patients was reported to be between 0.1% and
5.6%.[
The population-based studies in adult NPC survivors
have revealed excess head-and-neck SPMs within
the radiation field. The most common SPMs in this region
are sarcomas, oral-oropharyngeal carcinomas, and
non-melanoma skin cancers.[
Our patients showed a significant risk of the oral
cavity and pharyngeal cancers, which made up three
of nine SPMs. Three of the nine SPMs were sarcomas
(one osteosarcoma, one fibrosarcoma, and one highgrade
sarcoma). Overall, eight of the nine SPMs were
in the radiation field.
There is an uncertainty in estimating the exact incidence
of radiation-induced SPM because of the confounding
factors such as patient lifestyle, genetic abnormalities,
and received systemic chemotherapy.[
Among our eight SPM patients, whose malignancy
developed in the irradiation field, six were treated primarily
with complete surgical resection and three of
them died of SPM.
Diagnosis of SPM in an early stage and treatment
with surgical resection is important in survival. Physicians
should be cautious about second neoplasia risk
in radiation fields during follow-up and able to detect
early in pediatric NPC survivors.[
Since the most of the SPMs develop in the irradiation field, prospective clinical studies investigating dose reduction in the treatment of pediatric NPC should be considered and evaluated with further prospective trials.
Peer-review: Externally peer-reviewed.
Conflict of Interest: All authors declared no conflict of interest. Ethics Committee Approval: The study was approved by the Local Ethics Committee of Istanbul University Oncology Instıtute (No: 186362, Date: 27/04/2021).
Financial Support: None declared.
Authorship contributions: Concept - S.B.B., R.K., M.A.; Design - S.B.B., K.Ö., R.K., M.A.; Supervision - S.B.B., K.Ö., R.K., M.A.; Funding - None; Materials - S.B.B., K.Ö., R.K., M.A.; Data collection and/or processing - S.B.B., K.Ö., M.A.; Data analysis and/or interpretation - S.B.B., K.Ö., R.K., M.A.; Literature search - S.B.B., K.Ö., M.A.; Writing - S.B.B., K.Ö., M.A.; Critical review - M.A.