Incidence and clinical impact of sterilized disease and minimal residual disease after preoperative radiochemotherapy for rectal cancer.
OBJECTIVE
In advanced rectal cancer, chemoradiation can induce downstaging until complete disappearance of the tumor or its persistence in minimal form. The complete sterilized and the minimal residual disease often are considered similar. We evaluated the specific incidence of these two conditions and analyzed their impact in terms of local recurrence, distant metastasis, and survival.


METHODS
We studied 139 uT3/T4 N0/N+ rectal cancers, treated with preoperative chemoradiation and curative surgery after six to eight weeks. We evaluated ypTNM stage and tumoral regression, according to the five degrees proposed by Dworak, with special attention to 4 and 3 (sterilized and minimal residual disease).


RESULTS
Tumor downstaging occurred in 65 patients (46.7 percent), including 25 sterilized lesions (17.9 percent) and 24 minimal residual disease (17.2 percent). In median follow-up of 30 months, none of the patients with sterilized disease developed local or distant recurrence. Among patients with minimal residual disease, none developed local recurrence, whereas two (8.3 percent) developed distant metastasis, and one died from disease. In patients with gross residual disease (Grade 2, 1, 0) the percentage of local recurrence was 8.8 percent, distant recurrence 26.6 percent, and 13.3 percent died from disease. The difference between three groups is statistically significant as regards local and distant recurrence.


CONCLUSIONS
After preoperative therapy, the sterilized disease shows an excellent prognosis. The minimal residual disease has an important numeric incidence. Its outcome is different, with a not-negligible risk of distant recurrence. The minimal residual disease has a much better prognosis in comparison with the gross residual disease.
Gavioli
Margherita
M
III Division of Surgery, Policlinico Hospital, Modena, Italy. gavioli.margherita@policlinico.mo.it
Luppi
Gabriele
G
Losi
Lorena
L
Bertolini
Federica
F
Santantonio
Mario
M
Falchi
Anna Maria
AM
D'Amico
Roberto
R
Conte
Pier Franco
PF
Natalini
Gianni
G
D000230:Adenocarcinoma / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017024:Chemotherapy, Adjuvant; D003082:Colectomy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D018365:Neoplasm, Residual / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D012074:Remission Induction; D012189:Retrospective Studies; D016896:Treatment Outcome
D000970:Antineoplastic Agents