Oligometastatic disease

The oligometastatic disease is an intermediate state between locally advanced and disseminated or multimetastatic cancer [1]. It has been based on the number of detectable metastatic lesions in imaging exams, with the threshold varying between 3 and 10 lesions. Singh et al. [2] reported that a number of metastases limited to five lesions developed during follow-up after curative treatment of primary tumor were significantly associated with better 5-year survival (73% vs. 43% of patients with more than five metastases). Therefore, patients with oligometastatic disease are thought to have improved outcomes compared with those with multimetastatic cancer, with greater median survivals [3]. Until there is genomic or proteomic data that provide a biological component for the definition of oligometastatic disease, a clinical diagnosis based on specific cut-offs of the number of metastases (usually up to 5) and involved sites (usually up to 2) is reasonable [4,7]. Relapse may be local or distant. The molecular basis of oligometastases is that they can act like primary tumors and are able to seed and form new metastases [5].
In addition, a distinction is made between synchronous disease (de novo or primary metastases, untreated primary tumor) and metachronous disease (primary tumor previously treated and metastases are encountered during recurrence) [4]. For the definition of oligometastatic disease, these time and onset of metastasis (synchronous [de novo, within 3 months of primary diagnosis] versus metachronous [recurrent]) was also recently defined by the Dutch Oligometastatic Prostate Cancer Working Group [8]. An even more recent update is that of the ESTRO-EORTC consensus [6]:

Recorded at the 2016 World Conference of Lung Cancer (WCLC) of the International Association for the Study of Lung Cancer (IASLC) in Vienna, Austria.

Bibliographic references:

[1] Hellman S, Weichselbaum RR. Oligometastases. J Clin Oncol. 1995 Jan;13(1):8-10. Available at: https://doi.org/10.1200/JCO.1995.13.1.8.

[2] Singh D, Yi WS, Brasacchio RA, Muhs AG, Smudzin T, Williams JP, et al. Is there a favorable subset of patients with prostate cancer who develop oligometastases? Int J Radiat Oncol Biol Phys. 2004 Jan 1;58(1):3-10. Available at: https://doi.org/10.1016/S0360-3016(03)01442-1.

[3] Tree AC, Khoo VS, Eeles RA, Ahmed M, Dearnaley DP, Hawkins MA, et al. Stereotactic body radiotherapy for oligometastases. Lancet Oncol. 2013 Jan;14(1):e28-37. Available at: https://doi.org/10.1016/S1470-2045(12)70510-7.

[4] Tosoian JJ, Gorin MA, Ross AE, Pienta KJ, Tran PT, Schaeffer EM. Oligometastatic prostate cancer: definitions, clinical outcomes, and treatment considerations. Nat Rev Urol. 2017 Jan;14(1):15-25. Available at: https://doi.org/10.1038/nrurol.2016.175.

[5] Gundem G, Van Loo P, Kremeyer B, Alexandrov LB, Tubio JMC, Papaemmanuil E, et al. The evolutionary history of lethal metastatic prostate cancer. Nature. 2015 Apr 16;520(7547):353-357. Available at: https://doi.org/10.1038/nature14347.

[6] Guckenberger M, Lievens Y, Bouma AB, et al. Characterisation and classification of oligometastatic disease: a European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus recommendation. Lancet Oncol. 2020 Jan;21(1):e18-e28. Available at: https://doi.org/10.1016/s1470-2045(19)30718-1.
[7] Login | Mirrors of Medicine [Internet]. Ppcp.mirrorsmed.org. [cited 2019 Oct 13]. Available from: https://ppcp.mirrorsmed.org/assessment/review/gdzhyn8q6tc08wcg0ss8wgk08gcoww8.
[8] Aluwini SS, Mehra N, Lolkema MP, et al. Oligometastatic Prostate Cancer: Results of a Dutch Multidisciplinary Consensus Meeting [published online ahead of print, 2019 Aug 7]. Eur Urol Oncol. 2019;S2588-9311(19)30113-0. Available at: https://doi.org/10.1016/j.euo.2019.07.010.