Metachronous primary lung carcinoma

Metachronous primary lung carcinoma usually refers to tumors with the same histology which are "separated in time" when there has been a disease-free interval between cancers.

Its definition has been "variably" defined in the literature and can include:

• time interval of at least 2 years or the second tumor is found in a different segment, lobe, or lung with no carcinoma in the lymphatics common to both; and there is no evidence of extrapulmonary metastasis at the time of diagnosis ¹
• SEER database recommendation: 2-month period to distinguish between synchronous and metachronous multiple primaries.
• IARC suggestion: registration of synchronous tumors diagnosed in an interval of less than 6 months (or metachronous if more than 6 months) if arising in different sites
• "the latter two suggestions have been for "any" cancer and not just lung cancer"

Epidemiology

Average lifelong rate of developing a "new primary lung cancer" is thought to be approximately 1% and 6% per year after radical therapy for non-small-cell lung cancer and small cell lung cancer, respectively ⁴.

Differential diagnosis

• pulmonary metastasis from original initial lung cancer

See also

• synchronous primary lung carcinoma