METHODS
We analyzed data on 6179 patients who had lung, breast or prostate cancer as their first primary cancer.
All patients were recorded in the Cancer Registry Unit of the Health Directorate of Antalya Province
of Turkey. We analyzed the data concerning each of the three first primaries. We utilised Kaplan-Meier
survival analyses and log-rank test to compare the overall survival rates of patients with single primary
tumors and patients with multiple primary tumors. In addition, we stratified data according to age,
gender, number of primary tumors (patients with single primary, patients with multiple primaries), or
disease stage of the first primary (metastatic, non-metastatic). Lastly, potential prognostic factors were
separately evaluated in Cox-regression models.
RESULTS
We found that the overall survival of lung cancer patients with a single primary was shorter than that of
patients with multiple primaries (p<0.001). It was vice versa for breast and prostate cancer patients. Multivariate
analysis performed for lung cancer patients showed that male patients had a higher risk of exitus
than female patients. Lung cancer patients who had metastatic disease at the time of diagnosis had a higher
risk of exitus than patients who had a non-metastatic disease at the time of diagnosis (p<0.001).
CONCLUSION
We found that the inclusion of subsequent primary cancers in the overall survival analysis resulted in
higher survival for the patients with lung cancer as their first primary tumor. On the other hand, it was
associated with lower survival for patients with breast or prostate cancer as their first primary tumor.
Keywords: Breast cancer; lung cancer; multiple primary malignancies; prostate cancer; survival analysis
Due to the improvement in diagnostic tools, treatment
modalities and supportive care, survival time for
cancer patients has been prolonged and the number of
multiple primary cancers has increased continuously.
Crocetti et al. reported that 1.08% of the cancer survivors
were diagnosed with subsequent primary cancers.[
Rosso et al. reported that the general effects of the
inclusion of multiple primary tumours in survival
analyses is to reduce survival estimates.[
We also analyzed data concerning each three cancer
primaries according to gender, number of independent
primaries or disease extent of the first primary
(metastatic, non-metastatic). Kaplan-Meier method
was used for survival curves. Kaplan-Meier statistical
method is a non-parametric estimator of the survival
function.[
Estimated overall survival of lung cancer patients
without secondary (subsequent was meant by using
secondary) primaries was shorter than that of patients
with multiple primaries (p<0.001) (Fig.
Survival analyses of prostate cancer patients whose primary malignancies were diagnosed between the years of 2005-2010 showed that estimated survivals of prostate cancer patients without secondary (subsequent was meant by using secondary) tumors were higher than that of patients with multiple primary tumors (p<0.05). Multivariate analysis done for these prostate cancer patients showed that patients who had metastatic disease at the time of diagnosis had a higher risk of exitus than patients who had the non-metastatic disease at the time of diagnosis (p<0.001). In addition to this, patients who had only one primary cancer also had higher risk of exitus than patients who had multiple primaries (p<0.001). Lastly, survival analyses of breast cancer patients whose primary malignancies were diagnosed between the years of 2005-2010 showed that estimated survivals of breast cancer patients without secondary (subsequent was meant by using secondary) tumors were higher than that of patients with multiple primary tumors (p<0.003). Multivariate analysis performed for these breast cancer patients showed that patients who had metastatic disease at the time of diagnosis had a higher risk of exitus than patients who had the non-metastatic disease at the time of diagnosis (p<0.001).
Rosso et al. reported cancer multiplicity frequency
among cancer patients in Europe with an overall
proportion of 6.3%.[
In the literature, Ellison analyzed Canadian data
and reported a lower survival in multiple primary
cancers.[
Our study also had several limitations because this
study was conducted by the retrospective analysis of
the patients. Reachable data provided by the registry
unit were only used in the study. However, data collection to the registry of AİSMKKM was still ongoing at
the time of data gathering. Inclusion of new patients
and new data to the registry of AİSMKKM was going
on during the time the data included in this study was
given by the registry unit, which was one of the reasons
we chose the year 2005, not before. At the time
data was given by the registry unit, it was informed
that records of years before 2005 were incomplete. Furthermore,
overall survival was evaluated in our study.
Cancer-specific survival was not analyzed. Overall
survival could be affected by the presence of comorbidities,
particularly cardiovascular diseases, diabetes
mellitus and/or smoking.[
Acknowledgements: We would like to express our gratitude towards to Cancer Registry Unit of the Health Directorate of Antalya Province of Turkey (Antalya İl Sağlık Müdürlüğü Kanser Kayıt Merkezi) for providing us with their data. As the corresponding author of this study, I also want to thank my wife Fatma Avcı Merdin, for sharing her love and time during this period. Some of the related data of this study were presented as an abstract at the European Cancer Congress (ECCO 17, ESMO 38) September 27-October 1, 2013, Amsterdam, Holland. Related published Congress abstract no. Po1430 in Eur J Cancer 2013:49(Suppl 2). In addition, the corresponding author also wants to thank his father Hayri Merdin, his mother Zeynep Merdin and his brother Mustafa Kürşat Merdin for sharing their time. Lastly, the authors thank Health Directorate of Antalya Province of Turkey (Antalya İl Sağlık Müdürlüğü) for their permission to use the data of the Health Directorate of Antalya Province of Turkey.
Peer-review: Externally peer-reviewed.
Conflict of Interest: There are no conflicts of interest in this study.
Ethics Committee Approval: This study was approved by the local ethics committee.
Financial Support: We do not have any financial support for this study.
Authorship contributions: Concept - A.M., H.Ş.B.; Design - A.M., H.Ş.B.; Supervision - A.M., H.K., H.Ş.B.; Funding - A.M.; Materials - A.M., H.Ş.B., H.K.; Data processing - A.M., H.K., H.Ş.B.; Data gathering/collection from the Cancer Registry Unit of the Health Directorate of Antalya Province of Turkey - H.K.; Data analysis and/or interpretation - H.Ş.B.; Literature search - A.M., H.Ş.B.; Writing - A.M., H.K., H.Ş.B.; Critical review - A.M., H.K., H.Ş.B.
Footnotes: The corresponding author"s working address during the submission of the article was Hematology Clinic and Bone Marrow Transplantation Unit, University of Health Sciences Ankara Dr. Abdurrahman Yurtaslan Oncology Education and Research Hospital. In addition, this study was derived from and based on the thesis work (Medical Specialty Thesis, University of Akdeniz, Antalya, Turkey) of the author Alparslan Merdin.